All Solutions
Page 516: Getting Started
$f(-1)=(-1)^3-3(-1)^2-10(-1)+24= -1-3(1)+10+24=-1-3+10+24=30$
$f(4)=(4)^3-3(4)^2-10(4)+24=64-3(16)-40+24=64-48-40+24=0$
#### (b)
$f(-1)=dfrac{4(-1)}{1-(-1)}=dfrac{-4}{1+1}=dfrac{-4}{2}=-2$
$f(4)=dfrac{4(4)}{1-(4)}=dfrac{16}{1-4}=dfrac{16}{-3}=-5dfrac{1}{3}$
#### (c)
$f(-1)=3 log_{10}(-1)$
Since you cannot take the log of a negative number, the expression is undefined.
$f(4)= 3 log_{10}(4)=3(0.6021)=1.81$
#### (d)
$f(-1)= -5(0.5^{(-1-1)})=-5(0.5^{-2})=-5(4)=-20$
$f(4)=-5(0.5^{4-1})=-5(0.5^3)=-5(0.125)=-0.625$
The range is the $y$-values. From the graph, the range is $left{yinBbb{R}| yne2 right}$.
There is no minimum or maximum value.
The function is never increasing.
The function is decreasing from $(-infty, 1)$ and $(1, infty)$.
The function approaches $-infty$ as $x$ approaches $1$ from the left and $infty$ as $x$ approaches $1$ from the right.
The vertical asymptote is $x=1$.
The horizontal asymptote is $y=2$.
$textbf{The vertical stretch}$ turns the function into $y=|2x|$.
$textbf{The translation}$ $3$ units right turns the function into $y=|2x-3|$.
#### (b)
$textbf{The reflection}$ in the $x$-axis turns the function into $y=-cos{x}$.
$textbf{The horizontal compression}$ by a factor of $dfrac{1}{2}$ turns the function into $y=-cos{2x}$.
#### (c)
$textbf{The reflection}$ in the $y$-axis turns the function into $y=log_{3}(-x)$.
$textbf{The translation}$ $4$ units left makes the function $y=log{3}(-x-4)-1$.
#### (d)
$textbf{The vertical stretch}$ of $4$ turns the function into $y=dfrac{4}{x}$.
$textbf{The reflection}$ in the $x$-axis turns the function into $y=-dfrac{4}{x}$.
$textbf{The vertical translation}$ $5$ units down turns the function into $y=-dfrac{4}{x}-5$.
$2x^3-7x^2-5x+4=0$
By using $textbf{synthetic division}$, we get that one solution is $x=-1$.After that, we have next:
$2x^2-9x+4=0$
$(2x-1)(x-4)=0$
$2x-1=0$ or $x-4=0$
$2x=1$ or $x=4$
$x=dfrac{1}{2}$ or $x=4$
So, $textbf{the solutions are}$ $x=-1$, $x=dfrac{1}{2}$ or $x=4$.
#### (b)
$dfrac{2x+3}{x+3}+dfrac{1}{2}=dfrac{x+1}{x-1}$ $/2(x+3)(x-1)$
$2(2x+3)(x-1)+(x+3)(x-1)=2(x+1)(x+3)$
$2(2x^2-2x+3x-3)+x^2-x+3x-3=2(x^2+3x+x+3)$
$4x^2+2x-6+x^2+2x-3=2x^2+8x+6$
$3x^2-4x-15=0$
$(3x+5)(x-3)=0$
$x=-dfrac{5}{3}$ or $x=3$
So, $textbf{the solutions are}$ $x=-dfrac{5}{3}$, $x=3$.
$log{x}+log(x-3)=1$
$log(3(x-3))=1$
$10^1=x(x-3)$
$x^2-3x-10=0$
$(x-5)(x+2)=0$
$x=5$ or $x=-2$
Cannot take the $log$ of a negative number, so $x=5$.
#### (d)
$10^{-4x}-22=978$
$10^{-4x}=1000$
$-4x=3$
$x=-dfrac{3}{4}$
So, $textbf{the solution is}$ $x=-dfrac{3}{4}$.
$5^{x+3}-5^x=0.992$
$5^3cdot5^x-5^x=0.992$
$5^x(5^3-1)=0.992$
$5^x(125-1)=0.992$
$124cdot5^x=0.992$
$5^x=0.008$
$5^x=5^-3$
$x=-3$
So, $textbf{the solution is}$ $x=-3$.
$2cos^2{x}=sin{x}+1$
$2(sin^2{x}-1)=sin{x}+1$
$2sin^2{x}-sin{x}-3=0$
$(2sin{x}-3)(sin{x}+1)=0$
$2sin{x}-3=0$ or $sin{x}+1=0$
$2sin{x}-3=0$ or $sin{x}+1=0$
$sin{x}=dfrac{3}{2}$ or $sin{x}=-1$
Since $sin{x}$ cannot be greater than $1$, the first equation does not give a solution.
$sin{x}=-1$
$x=270^circ$
So, $textbf{the solution is}$ $x=270^circ$.
(d) $x=-dfrac{3}{4}$; (e) $x=-3$; (f) $x=270^circ$.
$x^3-x^2-14x+24<0$
Find the critical points by solving $x^3-x^2-14x+24=0$.By using $textbf{synthetic division}$, we get that $2$ is a critical value.
$x^2+x-12=0$
$(x+4)(x-3)=0$
$x+4=0$ or $x-3=0$
$x=-4$ or $x=3$
$textbf{The critical values are}$ $-4$, $2$ and $3$.Test points that are in the intervals created by the critical values:
$(x-2)(x-3)(x+4)$
Test $-5$: $(-)(-)(-)=(-)0$
Test $2.5$: $(+)(-)(+)=(-)0$
So, $textbf{the solution is}$ $(-infty,-4)$ $cup$ $(2,3)$.
$dfrac{(2x-3)(x-4)}{x+2}leq0$
Find $textbf{the critical values}$:
$2x-3=0$
$2x=3$
$x=dfrac{3}{2}$
$x-4=0$
$x=4$
$x+2=0$
$x=-2$
$textbf{The critical values are}$ $dfrac{3}{2}$, $4$ and $-2$.
Test $-3: (-)(-)div(-)=(-)0$
Test $2: (+)(-)div(+)=(-)0$
$textbf{The solution is}$ $(-2,dfrac{3}{2})$ $cup$ $[4,infty)$.
$f(x)=2sin(x-pi)$
$f(-x)=2sin(-x-pi)=-2sin(x-pi)$
So,it is odd.
#### (b)
$f(x)=dfrac{3}{4-x}$
$f(-x)=dfrac{3}{4-(-x)}=dfrac{3}{4+x}$
So, it is neither.
#### (c)
$f(x)=4x^4-3x^2$
$f(-x)=4(-x)^4-3(-x)^2=4x^4-3x^2$
So, it is even.
#### (d)
$f(x)=2^{3x-1}$
$f(-x)=2^{3(-x)-1}=2^{-3x-1}$
So, it is neither.