All Solutions
Page 380: Cumulative Review
$x^4+3x^3-4x^2-12x=0$
$(x^4+3x^3)+(-4x^2-12x)=0$
$x^3(x+3)-4x(x+3)=0$
$(x+2)(x^3-4x)=0$
$x(x+3)(x^2-4)=0$
$x(x+3)(x+2)(x-2)=0$
$x=0$ or $x=-3$ or $x=-2$ or $x=2$, so, we can conclude that $textbf{the correct answer is (d)}$.
$36=a(2+1)(2-1)(2-4)$
$36=a(3)(1)(-2)$
$a=-6$
So, $textbf{the equation is}$
$f(x)=-6(x+1)(x-1)(x-4)=-6(x^2-1)(x-4)=-6(x^3-4x^2-x+4)=-6x^3+24x^2+6x-24$
So, $textbf{the correct answer is}$ (b).
$2-4x < -5$
$-4x dfrac{7}{4}$
$-2$ is not greater than $dfrac{7}{4}$, so, $textbf{the correct answer is (a)}$.
$-15leq 3xleq3$
$-5leq xleq1$
$textbf{The correct answer is c)}$.
$textbf{The correct answer is a)}$.
$-5t^2+3.5t+10 > 10$
$-5t^2+3.5t > 0$
$t(-5t+3.5) > 0$
$textbf{The critical points are}$ $t=0$ and $t=0.7$.
Test:$-1: (-1)(-5(-1)+3.5) > 0 Rightarrow (-1)(5+3.5) > 0$ FALSE
Test $0.5: (0.5)(-5(0.5)+3.5) > 0 Rightarrow (0.5)(-2.5+3.5) > 0$ TRUE
Test $1: (1)(-5(1)+3.5) > 0 Rightarrow (1)(-5+3.5) > 0$ FALSE
So, $textbf{the solution is}$ $tin (0,0.7)$
$textbf{The correct answer is (b)}$.
Choice a) is not a posiible set of zeros only for the function.If the function has zeros only at $x=0$ and $x=1$, then the function has to increase to $(0, 0)$ and turn there and begin to decrease. Sometime before $x=1$, the function must turn again and increase to get back to the $x$-axis before $x=1$.
But this contradicts the given information that the function is decreasing for $0<x<2$.
$textbf{The correct answer is a)}$.
$f(-0.05)=2(-0.05)^3-4(-0.05)^2+6(-0.05)=-0.31025$
Find the rate of change using the points $(0,0)$ and $(-0.05,-0.31025)$.
$m=dfrac{-0.31025-0}{-0.05-0}=6.2$
$textbf{So, the correct answer is (c)}$.
$x(x-3)=0$
$x=0$ and $x=3$
Test $x=-1$: The function will be $(+)div(-)(-)=(+)$
So, the function is poitive to the left of zero.
Test $x=1$: The function will be $(+)div(+)(-)=(-)$
So,the function is negative between $0$ and $3$.
Test $x=4$: The function will be $(+)div(+)(+)=(+)$
So, the function is positive to the right of $3$.
$textbf{The function that matches this is c)}$.
$textbf{So, the correct answer is (c)}$.
$g(x)=dfrac{(x+3)(x-3)}{x-3}=x+3$.
$textbf{The correct answer is (d)}$.
Examine the behaviour of these functions for $-2<x<3$.
For choice a: Test $x=0:(+)div(+)=(+)$
For choice b: Test $x=0: (+)div(-)=(-)$
So, choice a is positive for $-2<x<3$
$textbf{The correct answer is a)}$.
Try $0.599$:
$(2-3(0.599))div(5(0.599)-3)=-40.6$
So, the function approaches $-infty$,
$textbf{The correct answer is d)}$.
$3-2x=3x(x+2)$
$3-2x=3x^2+6x$
$3x^2+8x-3=0$
$(3x-1)(x+3)=0$
$x=dfrac{1}{3}$ or $x=-3$.
$textbf{The correct answer is (c)}$.
$textbf{The correct answer is (d)}$.
$2x-3-dfrac{2}{x} leq 0$
$dfrac{2x^2}{x}-dfrac{3x}{x}-dfrac{2}{x} leq 0$
$dfrac{2x^2-3x-2}{x} leq 0$
$dfrac{(2x+1)(x-2)}{x} leq 0$
$textbf{So, the correct answer is (a)}$.
$x-3-dfrac{6}{x-2}>0$
$dfrac{x(x-2)}{x-2}-dfrac{3(x-2)}{x-2}-dfrac{6}{x-2}>0$
$dfrac{x^2-2x-3x+6-6}{x-2}>0$
$dfrac{x^2-5x}{x-2}>0$
$dfrac{x(x-5)}{x-2}>0$
The critical points are $0,5$ and $2$.
Test $-1: (-)(-)div(-)=(-)$ FALSE
Test $1: (+)(-)div(-)=(+)$ TRUE
Test $3 : (+)(-)div(+)=(-)$ FALSE
Test $6: (+)(+)div(+)=(+)$ TRUE
So, the solution is $(0, 2)$ and $(5, infty)$.
$textbf{The correct answer is d)}$.
$dfrac{G(a+h)-G(a)}{h}=dfrac{G(1.001)-G(1)}{0.001}=dfrac{0.9985-1}{0.001}=-1.5$
$textbf{So, the correct answer is (b)}$.
$textbf{So, the correct answer is (b)}$.
$textbf{So, the correct answer is (b)}$.
$135(dfrac{pi}{180})=dfrac{3pi}{4}$
$-270(dfrac{pi}{180})=-dfrac{3pi}{2}$
Each of the pairs of angles are equivalent, $textbf{so, the correct answer is (d)}$.
$pi-1.0517=2.09$
$textbf{The correct answer is (c)}$.
$(sqrt{3})^2+b^2=2^2$
$3+b^2=4$
$b^2=1$
$b=1$
The angle is in either in the third or fourth quadrant since the $sin$ is negative.
So, $cos theta=dfrac{1}{2}$ or $-dfrac{1}{2}$.
$tan theta=sqrt{3}$ when $cos theta=-dfrac{1}{2}$ or $-sqrt{3}$ when $cos theta=dfrac{1}{2}$.
$textbf{The correct answer is (a)}$.
$x=dfrac{pi}{6}$ and $x=dfrac{5pi}{6}$.
$textbf{So, the correct answer is (d)}$.
$y=3sin(2x)-1$.
$textbf{So, the correct answer is (b)}$.
$textbf{The correct answer is d)}$.
The maxmum height represented by choice c) is $18-23=-5$, not $41$ as required.
The maximum height represented by choice d) is $41-36=5$, not $41$ as required.
The maximum heigth represented by choice a) is $18+23=41$, as required.The minimum height represented by choice a) is $-18+23=5$, as required.
$textbf{The correct answer is a)}$.
$textbf{So, the correct answer is (c)}$.
$P(4)=23.7cos(dfrac{pi}{6}(4-7)+24.1)=24.1$
So, $textbf{the rate of change is }dfrac{24.1-3.575}{4-0}=5.13125$
$P(1)=23.7cos(dfrac{pi}{6}(1-7)+24.1)=0.4$
$P(7)=23.7cos(dfrac{pi}{6}(7-7)+24.1)=47.8$
So, $textbf{the rate of change is }dfrac{47.8-0.4}{7-1}=7.9$
$P(16)=23.7cos(dfrac{pi}{6}(16-7)+24.1)=24.1$
So, $textbf{the rate of change is }dfrac{24.1-47.8}{16-7}=-2.63$
$P(10)=23.7cos(dfrac{pi}{6}(10-7)+24.1)=24.1$
$P(18)=23.7cos(dfrac{pi}{6}(18-7)+24.1)=44.62$
So, $textbf{the rate of change is }dfrac{44.62-24.1}{18-10}=2.565$
$textbf{The correct answer is (b)}$.
length$=50-2x$
width$=40-2x$
$V=lwh$
$=(50-2x)(40-2x)x$
#### (b)
$6000=(50-2x)(40-2x)x$
$6000=(2000-80x-100x+4x^2)x$
$6000=2000x-180x^2+4x^3$
$0=4x^3-180x^2+2000x-6000$
$0=x^3-45x^2+500x-1500$
The possible reasonable solutions are $pm1, pm 2, pm 3, pm4,pm5,pm6,pm10,pm12, pm15, pm20$.
Use synthetic division to determine the solution…
So, $x=5$.
Now solve $x^2-40x+300=0$
$(x-10)(x-30)=0$
So, $x=10$ or $30$, but $30$ does not make sense in the context of the problem. So , $x=5$ or $x=10$.
#### (c)
Using a graphing calculator, find the relative maximum value.It occurs when $x=7.4$cm.
#### (d)
Using a graphing calculator, the range is $3<x<12.8$
$f(x): 0=x^2-5x+6$
$0=(x-3)(x-2)$
So, $x=3$ and $x=2$
$g(x): 0=x-3 Rightarrow x=3$
$dfrac{f(x)}{g(x)}: 0=dfrac{x^2-5x+6}{x-3}$
The function is undefined at $x=3$, so, the zero is $x=2$.
$dfrac{g(x)}{f(x)}: 0=dfrac{x-3}{x^2-5x+6}$
The function is undefined at $2$ and $3$, so, there are no zeros.
#### (b)
$dfrac{f(x)}{g(x)}:$ hole at $x=3$, no asymptotes
$dfrac{g(x)}{f(x)}:$ hole at $x=3$, asymptotes at $x=2$ and $y=0$
#### (c)
$dfrac{f(x)}{g(x)}:y=x-2$
$dfrac{g(x)}{f(x)}:y=-x$.
Vertical compressions and streches do not affect location of zeros; maximum and minimumm values are multiplied by the scale factor, but locations are unchanged; instantaneous rates of change are multiplied by the scale factor;
Horizontal compressions and strecthes move locations of zeros, maximus, and minimums toward or away from the $y$-axis by the reciprocal of the scale factor; instantaneous rates of change are multiplied by the reciprocal of scale factor; Vertical translations change location of zeros or remove them; maximum and minimum values are increased or decreased by the amount of the translation, but locations are unchanged; instantaneous rates of change are unchanged; Horizontal translations move location of zeros by the same amount as the translation;
maximum and minimum values are unchanged, but locations are moved by the same amount as the translation; instantaneous rates of change are unchanged, but locations are moved by the same amount as the translation.
$y=cos x$: Vertical compressions and stretches do not affect location of zeros; maximum and minimum values are multiplied by the scale factor,but locations are unchanged; instantaneous rates of change are multiplied by the scale factor; Horizontal compressions and stretches move locations of zeros,maximus, and minimums toward or away from the $y$-axis by the reciprocal of the scale factor; instantaneous rates of change are multiplied by the reciprocal of scale factor; Vertical translations change location of zeros or remove them; maximum and minimum values are increased or decreased by the amount of the translation, but locations are unchanged; instantaneous rates of change are unchanged; Horizontal translations move location of zeros by the same amount as the translation; maximum and minimum values are unchanged, but locations are moved by the same amount as the translation; instantaneous rates of change are unchanged, but locations are moved by the same amount as the translation.
$y=tan x$: Vertical compressions and stretches do not affect location of zeros; instantaneous rates of change are multiplied by the scale factor;
Horizontal compressions and stretches move locations of zeros toward or away from the $y$-axis by the reciprocal of the scale factor; instantaneous rates of change are multiplied by the reciprcal of scale factor; Vertical translations change location of zeros or remove them; instantaneous rates of change are unchanged; Horizontal translations move location of zeros by the same amount as translation; instantaneous rates of change are unchanged, but locations are moved by the same amount as the translation.