All Solutions
Page 542: Further Your Understanding
$(f div g)(x)=dfrac{5}{x}, xne0$
#### (b)
$(f div g)(x)=dfrac{4x}{2x-1}, xnedfrac{1}{2}$
#### (c)
$(fdiv g)(x)=dfrac{4x}{x^2+4}$
#### (d)
$(fdiv g)(x)=dfrac{(x+2)(sqrt{x-2})}{x-2}, x>2$
#### (e)
$(fdiv g)(x)=dfrac{8}{1+left(dfrac{1}{2} right)^x}$
#### (f)
$(fdiv g)(x)=dfrac{x^2}{log(x)}, x>0$
1(a):
1(a): domain of $f: left{xinBbb{R} right}$; domain of $g: left{xinBbb{R} right}$
1(b): domain of $f: left{xinBbb{R} right}$; domain of $g: left{xinBbb{R} right}$
1(c): domain of $f: left{xinBbb{R} right}$; domain of $g: left{xinBbb{R} right}$
1(d): domain of $f: left{xinBbb{R} right}$; domain of $g:left{ xinBbb{R}|xgeq 2right}$
1(e): domain of $f: left{xinBbb{R} right}$; domain of $g: left{xinBbb{R} right}$
1(f): domain of $f: left{xinBbb{R} right}$; domain of $g:left{xinBbb{R}|x > 0 right}$
1(a):
1(a): domain of $(fdiv g): left{xinBbb{R}|xne 0 right}$
1(b): domain of $(fdiv g): left{ xinBbb{R}|xne dfrac{1}{2}right}$
1(c): domain of $(fdiv g): left{xinBbb{R} right}$
1(d): domain of $(fdiv g): left{xinBbb{R}|x > 2 right}$
1(e): domain of $(fdiv g): left{xinBbb{R} right}$
1(f): domain of $(fdiv g): left{xin Bbb{R}|x > 0 right}$
$dfrac{260}{1+24(0.9)^t}=dfrac{260}{1+24(0.9)^{20}}=66$cm
textbf{The rate of change is $left[66-(260 div 25) right] div 20$ or $2.798$ cm/day.
}
#### (b)
The maximum height is $260$, so half of $260$ is $130$ cm.
$130=dfrac{260}{1+24(0.9)^t}$
$130+3120(0.9)^t=260$
$3120(0.9)^t=130$
$(0.9)^t=130 div 3120$
$tlog0.9=log(130 div 3120)$
$t=30$ days
#### (c)
$left(dfrac{260}{1+24(0.9)^{30.1}}-dfrac{260}{1+24 (0.9)^{30}} right)div 0.1= 6.848$ cm/day
#### (d)
It slows down and eventually comes to zero.This is seen on the graph as it becomes horizontal at the top.