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linear function : a function with a constant rate of change that is a polynomial of degree 1, and whose graph is a straight line
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model breakdown : when a model no longer applies after a certain point
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parallel lines : two or more lines with the same slope
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perpendicular lines : two lines that intersect at right angles and have slopes that are negative reciprocals of each other
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point-slope form : the equation for a line that represents a linear function of the formy−y1=m(x−x1)y−y1=m(x−x1)
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slope : the ratio of the change in output values to the change in input values; a measure of the steepness of a line
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slope-intercept form : the equation for a line that represents a linear function in the formf(x)=mx+bf(x)=mx+b
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vertical line : a line defined byx=a,x=a,whereaais a real number. The slope of a vertical line is undefined.
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A polynomial function of degree two is called a quadratic function.
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The graph of a quadratic function is a parabola. A parabola is a U-shaped curve that can open either up or down.
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The axis of symmetry is the vertical line passing through the vertex. The zeros, orx-x-intercepts, are the points at which the parabola crosses thex-x-axis. They-y-intercept is the point at which the parabola crosses they-y-axis. SeeExample 1,Example 7, andExample 8.
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Quadratic functions are often written in general form. Standard or vertex form is useful to easily identify the vertex of a parabola. Either form can be written from a graph. SeeExample 2.
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The vertex can be found from an equation representing a quadratic function. SeeExample 3.
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The domain of a quadratic function is all real numbers. The range varies with the function. SeeExample 4.
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A quadratic function’s minimum or maximum value is given by they-y-value of the vertex.
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The minimum or maximum value of a quadratic function can be used to determine the range of the function and to solve many kinds of real-world problems, including problems involving area and revenue. SeeExample 5andExample 6.
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The vertex and the intercepts can be identified and interpreted to solve real-world problems. SeeExample 9.
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A power function is a variable base raised to a number power. SeeExample 1.
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The behavior of a graph as the input decreases beyond bound and increases beyond bound is called the end behavior.
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The end behavior depends on whether the power is even or odd. SeeExample 2andExample 3.
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A polynomial function is the sum of terms, each of which consists of a transformed power function with positive whole number power. SeeExample 4.
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The degree of a polynomial function is the highest power of the variable that occurs in a polynomial. The term containing the highest power of the variable is called the leading term. The coefficient of the leading term is called the leading coefficient. SeeExample 5.
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The end behavior of a polynomial function is the same as the end behavior of the power function represented by the leading term of the function. SeeExample 6andExample 7.
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A polynomial of degreennwill have at mostnnx-intercepts and at mostn−1n−1turning points. SeeExample 8,Example 9,Example 10,Example 11, andExample 12.
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Polynomial functions of degree 2 or more are smooth, continuous functions. SeeExample 1.
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To find the zeros of a polynomial function, if it can be factored, factor the function and set each factor equal to zero. SeeExample 2,Example 3,andExample 4.
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Another way to find thex-x-intercepts of a polynomial function is to graph the function and identify the points at which the graph crosses thex-x-axis. SeeExample 5.
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The multiplicity of a zero determines how the graph behaves at thex-x-intercepts. SeeExample 6.
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The graph of a polynomial will cross the horizontal axis at a zero with odd multiplicity.
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The graph of a polynomial will touch the horizontal axis at a zero with even multiplicity.
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The end behavior of a polynomial function depends on the leading term.
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The graph of a polynomial function changes direction at its turning points.
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A polynomial function of degreennhas at mostn−1n−1turning points. SeeExample 7.
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To graph polynomial functions, find the zeros and their multiplicities, determine the end behavior, and ensure that the final graph has at mostn−1n−1turning points. SeeExample 8andExample 10.
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Graphing a polynomial function helps to estimate local and global extremas. SeeExample 11.
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The Intermediate Value Theorem tells us that iff(a)andf(b)f(a)andf(b)have opposite signs, then there exists at least one valueccbetweenaaandbbfor whichf(c)=0.f(c)=0.SeeExample 9.
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Polynomial long division can be used to divide a polynomial by any polynomial with equal or lower degree. SeeExample 1andExample 2.
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The Division Algorithm tells us that a polynomial dividend can be written as the product of the divisor and the quotient added to the remainder.
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Synthetic division is a shortcut that can be used to divide a polynomial by a binomial in the formx−k.x−k.SeeExample 3,Example 4,andExample 5.
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Polynomial division can be used to solve application problems, including area and volume. SeeExample 6.
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To findf(k),f(k),determine the remainder of the polynomialf(x)f(x)when it is divided byx−k.x−k.This is known as the Remainder Theorem. SeeExample 1.
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According to the Factor Theorem,kkis a zero off(x)f(x)if and only if(x−k)(x−k)is a factor off(x).f(x).SeeExample 2.
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According to the Rational Zero Theorem, each rational zero of a polynomial function with integer coefficients will be equal to a factor of the constant term divided by a factor of the leading coefficient. SeeExample 3andExample 4.
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When the leading coefficient is 1, the possible rational zeros are the factors of the constant term.
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Synthetic division can be used to find the zeros of a polynomial function. SeeExample 5.
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According to the Fundamental Theorem, every polynomial function has at least one complex zero. SeeExample 6.
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Every polynomial function with degree greater than 0 has at least one complex zero.
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Allowing for multiplicities, a polynomial function will have the same number of factors as its degree. Each factor will be in the form(x−c),(x−c),whereccis a complex number. SeeExample 7.
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The number of positive real zeros of a polynomial function is either the number of sign changes of the function or less than the number of sign changes by an even integer.
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The number of negative real zeros of a polynomial function is either the number of sign changes off(−x)f(−x)or less than the number of sign changes by an even integer. SeeExample 8.
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Polynomial equations model many real-world scenarios. Solving the equations is easiest done by synthetic division. SeeExample 9.
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We can use arrow notation to describe local behavior and end behavior of the toolkit functionsf(x)=1xf(x)=1xandf(x)=1x2.f(x)=1x2.SeeExample 1.
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A function that levels off at a horizontal value has a horizontal asymptote. A function can have more than one vertical asymptote. SeeExample 2.
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Application problems involving rates and concentrations often involve rational functions. SeeExample 3.
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The domain of a rational function includes all real numbers except those that cause the denominator to equal zero. SeeExample 4.
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The vertical asymptotes of a rational function will occur where the denominator of the function is equal to zero and the numerator is not zero. SeeExample 5.
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A removable discontinuity might occur in the graph of a rational function if an input causes both numerator and denominator to be zero. SeeExample 6.
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A rational function’s end behavior will mirror that of the ratio of the leading terms of the numerator and denominator functions. SeeExample 7,Example 8,Example 9, andExample 10.
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Graph rational functions by finding the intercepts, behavior at the intercepts and asymptotes, and end behavior. SeeExample 11.
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If a rational function hasx-intercepts atx=x1,x2,…,xn,x=x1,x2,…,xn,vertical asymptotes atx=v1,v2,…,vm,x=v1,v2,…,vm,and noxi=anyvj,xi=anyvj,then the function can be written in the form
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SeeExample 12.
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The inverse of a quadratic function is a square root function.
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Iff−1f−1is the inverse of a functionf,f,thenffis the inverse of the functionf−1.f−1.SeeExample 1.
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While it is not possible to find an inverse of most polynomial functions, some basic polynomials are invertible. SeeExample 2.
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To find the inverse of certain functions, we must restrict the function to a domain on which it will be one-to-one. SeeExample 3andExample 4.
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When finding the inverse of a radical function, we need a restriction on the domain of the answer. SeeExample 5andExample 7.
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Inverse and radical and functions can be used to solve application problems. SeeExample 6andExample 8.
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A relationship where one quantity is a constant multiplied by another quantity is called direct variation. SeeExample 1.
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Two variables that are directly proportional to one another will have a constant ratio.
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A relationship where one quantity is a constant divided by another quantity is called inverse variation. SeeExample 2.
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Two variables that are inversely proportional to one another will have a constant multiple. SeeExample 3.
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In many problems, a variable varies directly or inversely with multiple variables. We call this type of relationship joint variation. SeeExample 4.
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f ( x ) = a x 2 + b x + c f ( x ) = a x 2 + b x + c
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f ( x ) = a ( x − h ) 2 + k f ( x ) = a ( x − h ) 2 + k
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f ( x ) = a n x n + ... + a 2 x 2 + a 1 x + a 0 f ( x ) = a n x n + ... + a 2 x 2 + a 1 x + a 0
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f ( x ) = d ( x ) q ( x ) + r ( x ) where q ( x ) ≠0 f ( x ) = d ( x ) q ( x ) + r ( x ) where q ( x ) ≠0
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f ( x ) = P ( x ) Q ( x ) = a p x p + a p − 1 x p − 1 + ... + a 1 x + a 0 b q x q + b q − 1 x q − 1 + ... + b 1 x + b 0 , Q ( x ) ≠0 f ( x ) = P ( x ) Q ( x ) = a p x p + a p − 1 x p − 1 + ... + a 1 x + a 0 b q x q + b q − 1 x q − 1 + ... + b 1 x + b 0 , Q ( x ) ≠0
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y = k x n , k y = k x n , k is a nonzero constant.
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y = k x n , k y = k x n , k is a nonzero constant.
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arrow notation : a way to represent symbolically the local and end behavior of a function by using arrows to indicate that an input or output approaches a value
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axis of symmetry : a vertical line drawn through the vertex of a parabola, that opens up or down, around which the parabola is symmetric; it is defined byx=−b2a.x=−b2a.
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coefficient : a nonzero real number multiplied by a variable raised to an exponent
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constant of variation : the non-zero valuekkthat helps define the relationship between variables in direct or inverse variation
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continuous function : a function whose graph can be drawn without lifting the pen from the paper because there are no breaks in the graph
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degree : the highest power of the variable that occurs in a polynomial
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Descartes’ Rule of Signs : a rule that determines the maximum possible numbers of positive and negative real zeros based on the number of sign changes off(x)f(x)andf(−x)f(−x)
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direct variation : the relationship between two variables that are a constant multiple of each other; as one quantity increases, so does the other
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Division Algorithm : given a polynomial dividendf(x)f(x)and a non-zero polynomial divisord(x)d(x)where the degree ofd(x)d(x)is less than or equal to the degree off(x)f(x), there exist unique polynomialsq(x)q(x)andr(x)r(x)such thatf(x)=d(x)q(x)+r(x)f(x)=d(x)q(x)+r(x)whereq(x)q(x)is the quotient andr(x)r(x)is the remaind...
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end behavior : the behavior of the graph of a function as the input decreases without bound and increases without bound
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Factor Theorem : kkis a zero of polynomial functionf(x)f(x)if and only if(x−k)(x−k)is a factor off(x)f(x)
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Fundamental Theorem of Algebra : a polynomial function with degree greater than 0 has at least one complex zero
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general form of a quadratic function : the function that describes a parabola, written in the formf(x)=ax2+bx+cf(x)=ax2+bx+c, wherea,b,a,b,andccare real numbers andaâ‰0.aâ‰0.
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global maximum : highest turning point on a graph;f(a)f(a)wheref(a)≥f(x)f(a)≥f(x)for allx.x.
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global minimum : lowest turning point on a graph;f(a)f(a)wheref(a)≤f(x)f(a)≤f(x)for allx.x.
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horizontal asymptote : a horizontal liney=by=bwhere the graph approaches the line as the inputs increase or decrease without bound.
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Intermediate Value Theorem : for two numbersaaandbbin the domain off,f,ifa<ba<bandf(a)â‰f(b),f(a)â‰f(b),then the functionfftakes on every value betweenf(a)f(a)andf(b)f(b); specifically, when a polynomial function changes from a negative value to a positive value, the function must cross thex-x-axis
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inverse variation : the relationship between two variables in which the product of the variables is a constant
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inversely proportional : a relationship where one quantity is a constant divided by the other quantity; as one quantity increases, the other decreases
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invertible function : any function that has an inverse function
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joint variation : a relationship where a variable varies directly or inversely with multiple variables
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