All Solutions
Page 167: Check Your Understanding
$sqrt{a^{2} cdot b}=asqrt{b}$
To apply this, factor the expression under the radical sign such that one factor is a perfect square.
b) $sqrt{50}=sqrt{25cdot 2}=sqrt{5^2cdot 2}=5sqrt{2}$
c) $sqrt{98}=sqrt{49cdot 2}=sqrt{7^2cdot 2}=7sqrt{2}$
d) $sqrt{32}=sqrt{16cdot 2}=sqrt{4^2cdot 2}=4sqrt{2}$
b) $5sqrt{2}$
c) $7sqrt{2}$
d) $4sqrt{2}$
$asqrt{b}times csqrt{d}=(acdot c)sqrt{(bcdot d)}$
b) $sqrt{11}timessqrt{6}=sqrt{11times 6}=sqrt{66}$
c) $2sqrt{3}times 5sqrt{2}=(2cdot 5)sqrt{3cdot 2}=10sqrt{6}$
d) $-4sqrt{3}times 8sqrt{13}=(-4cdot 8)sqrt{3cdot 13}=-32sqrt{39}$
b) $sqrt{66}$
c) $10sqrt{6}$
d) $-32sqrt{39}$
$$
asqrt{m} + bsqrt{m}+ csqrt{n}+dsqrt{n}=(a+b)sqrt{m}+(c+d)sqrt{n}
$$
$=(4+3)sqrt{5}$
$=7sqrt{5}$
$bold{b)}$ $9sqrt{7}-4sqrt{7}$
$=(9-4)sqrt{7}$
$=5sqrt{7}$
$bold{c)}$ $3sqrt{3}+8sqrt{2}-4sqrt{3}+11sqrt{2}$
$=(3-4)sqrt{8}+(8+11)sqrt{2}$
$=-sqrt{8}+19sqrt{2}$
$bold{d)}$ $sqrt{8}-sqrt{18}$
$=sqrt{4cdot 2}-sqrt{9cdot 2}$
$=sqrt{2^2cdot 2}-sqrt{3^2cdot 2}$
$=2sqrt{2}-3sqrt{2}$
$=(2-3)sqrt{2}$
$=-sqrt{2}$
b) $5sqrt{7}$
c) $-sqrt{8} +19sqrt{2}$
d) $-sqrt{2}$
$sqrt{a^{2} cdot b}=asqrt{b}$
To apply this, factor the expression under the radical sign such that one factor is a perfect square.
$=3sqrt{4cdot 3}$
$=3sqrt{2^2cdot 3}$
$=3cdot (2sqrt{3})$
$$
=6sqrt{3}
$$
$=-5sqrt{25cdot 5}$
$=-5sqrt{5^2cdot 5}$
$=-5cdot (5sqrt{5})$
$$
=-25sqrt{5}
$$
$=10sqrt{4cdot 10}$
$=10sqrt{2^2cdot 10}$
$=10(2sqrt{10})$
$=20sqrt{10}$
$=-dfrac{1}{2}sqrt{4cdot 15}$
$=-dfrac{1}{2}sqrt{2^2cdot 15}$
$=-dfrac{1}{2}cdot 2sqrt{15}$
$=-sqrt{15}$
$=dfrac{2}{3}sqrt{9cdot 5}$
$=dfrac{2}{3}sqrt{3^2cdot 5}$
$=dfrac{2}{3}cdot 3sqrt{5}$
$$
=2sqrt{5}
$$
$=-dfrac{9}{10}sqrt{20^2cdot 3}$
$=-dfrac{9}{10}cdot 20sqrt{3}$
$$
=-18sqrt{3}
$$
b) $-25sqrt{5}$
c) $20sqrt{10}$
d) $-sqrt{15}$
e) $2sqrt{5}$
f) $-18sqrt{3}$
,$ is equivalent to
$$
begin{align*}
sqrt{3}(2)-sqrt{3}(sqrt{5})
.end{align*}
$$
Using the properties of radicals, the expression above is equivalent to
$$
begin{align*}
&
2sqrt{3}-sqrt{3(5)}
\&=
2sqrt{3}-sqrt{15}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
2sqrt{2}(sqrt{7})+2sqrt{2}(3sqrt{3})
.end{align*}
$$
Using the properties of radicals, the expression above is equivalent to
$$
begin{align*}
&
2sqrt{2(7)}+2(3)sqrt{2(3)}
\&=
2sqrt{14}+6sqrt{6}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
(4sqrt{2})(4sqrt{2})
.end{align*}
$$
Using the properties of radicals, the expression above is equivalent to
$$
begin{align*}
&
4(4)sqrt{2(2)}
\&=
16sqrt{(2)^2}
\&=
16(2)
\&=
32
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
(-2sqrt{3})(-2sqrt{3})(-2sqrt{3})
.end{align*}
$$
Using the properties of radicals, the expression above is equivalent to
$$
begin{align*}
&
-2(-2)(-2)sqrt{3(3)(3)}
\&=
-8sqrt{27}
.end{align*}
$$
Extracting the factor of the radicand that is a perfect power of the index, the expression above is equivalent to
$$
begin{align*}
&
-8sqrt{9cdot3}
\&=
-8sqrt{(3)^2cdot3}
\&=
-8(3)sqrt{3}
\&=
-24sqrt{3}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
4(3)sqrt{3(6)}
\&=
12sqrt{18}
.end{align*}
$$
Extracting the factor of the radicand that is a perfect power of the index, the expression above is equivalent to
$$
begin{align*}
&
12sqrt{9cdot2}
\&=
12sqrt{(3)^2cdot2}
\&=
12(3)sqrt{2}
\&=
36sqrt{2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
-7(5)sqrt{2(8)}
\&=
-35sqrt{16}
.end{align*}
$$
Extracting the factor of the radicand that is a perfect power of the index, the expression above is equivalent to
$$
begin{align*}
&
-35sqrt{(4)^2}
\&=
-35(4)
\&=
140
.end{align*}
$$
b) $2sqrt{14}+6sqrt{6}$
c) $32$
d) $-24sqrt{3}$
e) $36sqrt{2}$
f) $140$
,$ is equivalent to
$$
begin{align*}
&
sqrt{4cdot2}-sqrt{16cdot2}
\&=
sqrt{(2)^2cdot2}-sqrt{(4)^2cdot2}
\&=
2sqrt{2}-4sqrt{2}
.end{align*}
$$
By combining like radicals, the expression above is equivalent to
$$
begin{align*}
&
(2-4)sqrt{2}
\&=
-2sqrt{2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
sqrt{4cdot3}+sqrt{9cdot2}-sqrt{9cdot3}+sqrt{25cdot2}
\&=
sqrt{(2)^2cdot3}+sqrt{(3)^2cdot2}-sqrt{(3)^2cdot3}+sqrt{(5)^2cdot2}
\&=
2sqrt{3}+3sqrt{2}-3sqrt{3}+5sqrt{2}
.end{align*}
$$
By combining like radicals, the expression above is equivalent to
$$
begin{align*}
&
(2sqrt{3}-3sqrt{3})+(3sqrt{2}+5sqrt{2})
\&=
(2-3)sqrt{3}+(3+5)sqrt{2}
\&=
-sqrt{3}+8sqrt{2}
\&=
8sqrt{2}-sqrt{3}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
3sqrt{49cdot2}-5sqrt{36cdot2}
\&=
3sqrt{(7)^2cdot2}-5sqrt{(6)^2cdot2}
\&=
3(7)sqrt{2}-5(6)sqrt{2}
\&=
21sqrt{2}-30sqrt{2}
.end{align*}
$$
By combining like radicals, the expression above is equivalent to
$$
begin{align*}
&
(21-30)sqrt{2}
\&=
-9sqrt{2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
-4sqrt{100cdot2}+5sqrt{121cdot2}
\&=
-4sqrt{(10)^2cdot2}+5sqrt{(11)^2cdot2}
\&=
-4(10)sqrt{2}+5(11)sqrt{2}
\&=
-40sqrt{2}+55sqrt{2}
.end{align*}
$$
By combining like radicals, the expression above is equivalent to
$$
begin{align*}
&
(-40+55)sqrt{2}
\&=
15sqrt{2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
-5sqrt{9cdot5}+sqrt{4cdot13}+3sqrt{25cdot5}
\&=
-5sqrt{(3)^2cdot5}+sqrt{(2)^2cdot13}+3sqrt{(5)^2cdot5}
\&=
-5(3)sqrt{5}+2sqrt{13}+3(5)sqrt{5}
\&=
-15sqrt{5}+2sqrt{13}+15sqrt{5}
.end{align*}
$$
By combining like radicals, the expression above is equivalent to
$$
begin{align*}
&
(-15sqrt{5}+15sqrt{5})+2sqrt{13}
\&=
0+2sqrt{13}
\&=
2sqrt{13}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
7sqrt{4cdot3}-3sqrt{4cdot7}+dfrac{1}{2}sqrt{16cdot3}+dfrac{2}{3}sqrt{9cdot7}
\&=
7sqrt{(2)^2cdot3}-3sqrt{(2)^2cdot7}+dfrac{1}{2}sqrt{(4)^2cdot3}+dfrac{2}{3}sqrt{(3)^2cdot7}
\&=
7(2)sqrt{3}-3(2)sqrt{7}+dfrac{1}{2}(4)sqrt{3}+dfrac{2}{3}(3)sqrt{7}
\&=
14sqrt{3}-6sqrt{7}+2sqrt{3}+2sqrt{7}
.end{align*}
$$
By combining like radicals, the expression above is equivalent to
$$
begin{align*}
&
(14sqrt{3}+2sqrt{3})+(-6sqrt{7}+2sqrt{7})
\&=
(14-6)sqrt{3}+(-6+2)sqrt{7}
\&=
8sqrt{3}-4sqrt{7}
.end{align*}
$$
b) $8sqrt{2}-sqrt{3}$
c) $-9sqrt{2}$
d) $15sqrt{2}$
e) $2sqrt{13}$
f) $8sqrt{3}-4sqrt{7}$
,$ is equivalent to
$$
begin{align*}
&
6(3)+6(2sqrt{10})-sqrt{5}(3)-sqrt{5}(2sqrt{10})
.end{align*}
$$
Using the properties of radicals, the expression above simplifies to
$$
begin{align*}
&
18+12sqrt{10}-3sqrt{5}-2sqrt{5(10)}
\&=
18+12sqrt{10}-3sqrt{5}-2sqrt{50}
\&=
18+12sqrt{10}-3sqrt{5}-2sqrt{25cdot2}
\&=
18+12sqrt{10}-3sqrt{5}-2sqrt{(5)^2cdot2}
\&=
18+12sqrt{10}-3sqrt{5}-2(5)sqrt{2}
\&=
18+12sqrt{10}-3sqrt{5}-10sqrt{2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
(2)^2+2(2)(3sqrt{3})+(3sqrt{3})^2
\&=
4+12sqrt{3}+9(3)
\&=
4+12sqrt{3}+27
\&=
31+12sqrt{3}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
(sqrt{2})^2-(sqrt{5})^2
\&=
2-5
\&=
-3
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
3sqrt{3}(sqrt{3})+3sqrt{3}(-2sqrt{2})+4sqrt{2}(sqrt{3})+4sqrt{2}(-2sqrt{2})
.end{align*}
$$
Using the properties of radicals, the expression above simplifies to
$$
begin{align*}
&
3(sqrt{3})^2+3(-2)sqrt{3(2)}+4sqrt{2(3)}+4(-2)(sqrt{2})^2
\&=
3(3)-6sqrt{6}+4sqrt{6}-8(2)
\&=
9-6sqrt{6}+4sqrt{6}-16
.end{align*}
$$
By combining like terms, the expression above is equivalent to
$$
begin{align*}
&
(9-16)+(-6sqrt{6}+4sqrt{6})
\&=
-7-2sqrt{6}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
(2sqrt{5})^2-2(2sqrt{5})(3sqrt{7})+(3sqrt{7})^2
.end{align*}
$$
Using the properties of radicals, the expression above simplifies to
$$
begin{align*}
&
4(5)-2(2)(3)sqrt{5(7)}+9(7)
\&=
20-12sqrt{35}+63
\&=
83-12sqrt{35}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
[(1-sqrt{3})(2+sqrt{6})](5+sqrt{2})
\&=
[1(2)+1(sqrt{6})-sqrt{3}(2)-sqrt{3}(sqrt{6})](5+sqrt{2})
\&=
[2+sqrt{6}-2sqrt{3}-sqrt{18}](5+sqrt{2})
\&=
[2+sqrt{6}-2sqrt{3}-3sqrt{2}](5+sqrt{2})
.end{align*}
$$
Using the Distributive Property, the expression above simplifies to
$$
begin{align*}
&
2(5)+2(sqrt{2})+sqrt{6}(5)+sqrt{6}(sqrt{2})-2sqrt{3}(5)-2sqrt{3}(sqrt{2})-3sqrt{2}(5)-3sqrt{2}(sqrt{2})
\&=
10+2sqrt{2}+5sqrt{6}+sqrt{12}-10sqrt{3}-2sqrt{6}-15sqrt{2}-3sqrt{4}
\&=
10+2sqrt{2}+5sqrt{6}+2sqrt{3}-10sqrt{3}-2sqrt{6}-15sqrt{2}-6
\&=
(10-6)+(2sqrt{2}-15sqrt{2})+(5sqrt{6}-2sqrt{6})+(2sqrt{3}-10sqrt{3})
\&=
4-13sqrt{2}+3sqrt{6}-8sqrt{3}
.end{align*}
$$
b) $31+12sqrt{3}$
c) $-3$
d) $-7-2sqrt{6}$
e) $83-12sqrt{35}$
f) $4-13sqrt{2}+3sqrt{6}-8sqrt{3}$
$x^2=4^2+4^2$
$x^2=16+16$
$x^2=32$
$x=pmsqrt{32}$
Since $x$ can not take positive values,
$x=sqrt{32}$
$x=sqrt{16cdot 2}$
$x=sqrt{4^2cdot 2}$
$x=4sqrt{2}$ cm
$A=s^2$
In this case, we are given $A=450$ $text{cm}^2$ and we shall find $s$
$s^2=450; text{cm}^2$
Take the square root of both sides.
$s=sqrt{450}$ cm
$s=sqrt{225cdot 2}$ cm
$s=sqrt{15^2cdot 2}$ cm
$s=15sqrt{2}$ cm
$s=sqrt{450}$
$s=sqrt{25*9*2}$
$s=(5*3)sqrt{2}$
$$
s=15sqrt{2}
$$
$A=s^2$
Solving for s will yield the side lengths
15sqrt{2}
$$
In this case, we want to find $c$ given $a$ and $b$
$c^2=a^2+b^2$
$c^2=3^2+9^2$
$c^2=9+81$
$c^2=90$
$c=sqrt{90}$
$c=sqrt{9cdot 10}$
$c=sqrt{3^2cdot 10}$
$c=3sqrt{10}$
Therefore, the diagonal is $3sqrt{10}$ cm long.
,$ then
$$
begin{align*}
x_1&=
-2
\x_2&=
4
\y_1&=
7
\y_2&=
1
.end{align*}
$$
Using the Distance Formula which is given by $d=sqrt{(x_1-x_2)^2+(y_1-y_2)^2}
,$ then
$$
begin{align*}
d&=sqrt{(-2-4)^2+(7-1)^2}
\
d&=sqrt{(-6)^2+(6)^2}
\
d&=sqrt{36+36}
\
d&=sqrt{72}
\
d&=sqrt{36cdot2}
\
d&=sqrt{(6)^2cdot2}
\
d&=6sqrt{2}
.end{align*}
$$
Hence, the distance is $6sqrt{2} text{ units}
.$
6sqrt{2} text{ units}
$$
To simplify, remember the radical rule: $sqrt{a^2cdot b}=asqrt{b}$
$;;;=2sqrt{2}+3sqrt{4cdot 2}+sqrt{16cdot 5}$
$;;;=2sqrt{2}+3cdot 2sqrt{2}+4sqrt{5}$
$;;;=2sqrt{2}+6sqrt{2}+4sqrt{5}$
$;;;=(2+6)sqrt{2}+4sqrt{5}$
$$
P=8sqrt{2}+4sqrt{5}
$$
P=8sqrt{2}+4sqrt{5}
$$
,$ is equivalent to
$$
begin{align*}
&
left( sqrt{a} right)^2+2left( sqrt{a} right)left(sqrt{b} right)+left(sqrt{b} right)^2
\&=
a+2left( sqrt{ab} right)+b
text{ (Equation 1)}
.end{align*}
$$
With $a>0$ and $b>0,$ the expression, $sqrt{a^2}+sqrt{b^2}
,$ simplifies to
$$
begin{align*}
a+b
text{ (Equation 2)}
.end{align*}
$$
Since Equation $1$ contains an extra term ($2sqrt{ab}$) which is nonzero, then Equation $1$ is greater than Equation $2$.
:$
$$
begin{align*}
10sqrt{2}Rightarrow&
sqrt{(10)^2cdot2}
\&=
sqrt{100cdot2}
\&=
sqrt{200}
,\\
5sqrt{8}Rightarrow&
sqrt{(5)^2cdot8}
\&=
sqrt{25cdot8}
\&=
sqrt{200}
,\\
2sqrt{50}Rightarrow&
sqrt{(2)^2cdot50}
\&=
sqrt{4cdot50}
\&=
sqrt{200}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
sqrt{a^2cdot a}
.end{align*}
$$
Using $sqrt{x^2}=|x|,$ the expression above is equivalent to
$$
begin{align*}
&
|a|sqrt{a}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
sqrt{x^4y^6cdot x}
\&=
sqrt{(x^2y^3)^2cdot x}
.end{align*}
$$
Using $sqrt{x^2}=|x|,$ the expression above is equivalent to
$$
begin{align*}
&
|x^2y^3|sqrt{x}
\&=
|x^2y^2|cdot|y|sqrt{x}
\&=
x^2y^2|y|sqrt{x}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
5sqrt{n^6cdot n}-2nsqrt{n^4cdot n}
\&=
5sqrt{(n^3)^2cdot n}-2nsqrt{(n^2)^2cdot n}
.end{align*}
$$
Using $sqrt{x^2}=|x|,$ the expression above is equivalent to
$$
begin{align*}
&
5|n^3|sqrt{n}-2n|n^2|sqrt{n}
\&=
5|n^2|cdot|n|sqrt{n}-2n|n^2|sqrt{n}
\&=
5(n^2)cdot|n|sqrt{n}-2n(n^2)sqrt{n}
\&=
5n^2|n|sqrt{n}-2n^3sqrt{n}
\&=
left( 5n^2|n|-2n^3 right)sqrt{n}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
sqrt{p}(sqrt{q})-sqrt{p}(sqrt{p})+2sqrt{q}(sqrt{q})+2sqrt{q}(-sqrt{p})
.end{align*}
$$
Using the properties of radicals, the expression above is equivalent to
$$
begin{align*}
&
sqrt{pq}-p+2q-2sqrt{pq}
\&=
-p+2q+(sqrt{pq}-2sqrt{pq})
\&=
-p+2q-sqrt{pq}
.end{align*}
$$
b) $x^2y^2|y|sqrt{x}$
c) $left( 5n^2|n|-2n^3 right)sqrt{n}$
d) $-p+2q-sqrt{pq}$
$sqrt{sqrt{(sqrt{4096})}}$
$=sqrt{sqrt{(sqrt{64^2})}}$
$=sqrt{sqrt{64}}$
$=sqrt{sqrt{8^2}}$
$=sqrt{8}$
$=sqrt{4cdot 2}$
$=sqrt{2^2cdot 2}$
$$
=2sqrt{2}
$$
2sqrt{2}
$$
$=sqrt{sqrt{64}}$
$=sqrt{8}$
$=sqrt{4*2}$
$$
=2sqrt{2}
$$
2sqrt{2}
$$
Also, remember that $sqrt{a}=a^{1/2}$
$(sqrt{2})^x=256$
$(2^{1/2})^x=256$
$2^{frac{1}{2}x}=32cdot 8$
$2^{frac{1}{2}x}=2^5cdot 2^3$
$2^{frac{1}{2}x}=2^8$
$dfrac{1}{2}x=8$
$$
x=16
$$
x=16
$$