# 9.6 Solve equations with square roots  (Page 5/6)

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In the following exercises, check whether the given values are solutions.

For the equation $\sqrt{x+12}=x$ :
Is $x=4$ a solution?
Is $x=-3$ a solution?

$\text{yes}$ $\text{no}$

For the equation $\sqrt{\text{−}y+20}=y$ :
Is $y=4$ a solution?
Is $y=-5$ a solution?

For the equation $\sqrt{t+6}=t$ :
Is $t=-2$ a solution?
Is $t=3$ a solution?

no yes

For the equation $\sqrt{u+42}=u$ :
Is $u=-6$ a solution?
Is $u=7$ a solution?

In the following exercises, solve.

$\sqrt{5y+1}=4$

3

$\sqrt{7z+15}=6$

$\sqrt{5x-6}=8$

14

$\sqrt{4x-3}=7$

$\sqrt{2m-3}-5=0$

14

$\sqrt{2n-1}-3=0$

$\sqrt{6v-2}-10=0$

$17$

$\sqrt{4u+2}-6=0$

$\sqrt{5q+3}-4=0$

$\frac{13}{5}$

$\sqrt{4m+2}+2=6$

$\sqrt{6n+1}+4=8$

$\frac{5}{2}$

$\sqrt{2u-3}+2=0$

$\sqrt{5v-2}+5=0$

$\text{no solution}$

$\sqrt{3z-5}+2=0$

$\sqrt{2m+1}+4=0$

$\text{no solution}$

$\sqrt{u-3}+3=u$
$\sqrt{x+1}-x+1=0$

$\sqrt{v-10}+10=v$
$\sqrt{y+4}-y+2=0$

$10,11$ $5$

$\sqrt{r-1}-r=-1$
$\sqrt{z+100}-z+10=0$

$\sqrt{s-8}-s=-8$
$\sqrt{w+25}-w+5=0$

$8,9$ $11$

$3\sqrt{2x-3}-20=7$

$2\sqrt{5x+1}-8=0$

$3$

$2\sqrt{8r+1}-8=2$

$3\sqrt{7y+1}-10=8$

$5$

$\sqrt{3u-2}=\sqrt{5u+1}$

$\sqrt{4v+3}=\sqrt{v-6}$

not a real number

$\sqrt{8+2r}=\sqrt{3r+10}$

$\sqrt{12c+6}=\sqrt{10-4c}$

$\frac{1}{4}$

$\sqrt{a}+2=\sqrt{a+4}$
$\sqrt{b-2}+1=\sqrt{3b+2}$

$\sqrt{r}+6=\sqrt{r+8}$
$\sqrt{s-3}+2=\sqrt{s+4}$

$\text{no solution}$ $\frac{57}{16}$

$\sqrt{u}+1=\sqrt{u+4}$
$\sqrt{n-5}+4=\sqrt{3n+7}$

$\sqrt{x}+10=\sqrt{x+2}$
$\sqrt{y-2}+2=\sqrt{2y+4}$

$\text{no solution}$ 6

$\sqrt{2y+4}+6=0$

$\sqrt{8u+1}+9=0$

no solution

$\sqrt{a}+1=\sqrt{a+5}$

$\sqrt{d}-2=\sqrt{d-20}$

36

$\sqrt{6s+4}=\sqrt{8s-28}$

$\sqrt{9p+9}=\sqrt{10p-6}$

15

Use Square Roots in Applications

In the following exercises, solve. Round approximations to one decimal place.

Landscaping Reed wants to have a square garden plot in his backyard. He has enough compost to cover an area of 75 square feet. Use the formula $s=\sqrt{A}$ to find the length of each side of his garden. Round your answer to the nearest tenth of a foot.

Landscaping Vince wants to make a square patio in his yard. He has enough concrete to pave an area of 130 square feet. Use the formula $s=\sqrt{A}$ to find the length of each side of his patio. Round your answer to the nearest tenth of a foot.

$11.4\phantom{\rule{0.2em}{0ex}}\text{feet}$

Gravity While putting up holiday decorations, Renee dropped a light bulb from the top of a 64 foot tall tree. Use the formula $t=\frac{\sqrt{h}}{4}$ to find how many seconds it took for the light bulb to reach the ground.

Gravity An airplane dropped a flare from a height of 1024 feet above a lake. Use the formula $t=\frac{\sqrt{h}}{4}$ to find how many seconds it took for the flare to reach the water.

$8\phantom{\rule{0.2em}{0ex}}\text{seconds}$

Gravity A hang glider dropped his cell phone from a height of 350 feet. Use the formula $t=\frac{\sqrt{h}}{4}$ to find how many seconds it took for the cell phone to reach the ground.

Gravity A construction worker dropped a hammer while building the Grand Canyon skywalk, 4000 feet above the Colorado River. Use the formula $t=\frac{\sqrt{h}}{4}$ to find how many seconds it took for the hammer to reach the river.

$15.8\phantom{\rule{0.2em}{0ex}}\text{seconds}$

Accident investigation The skid marks for a car involved in an accident measured 54 feet. Use the formula $s=\sqrt{24d}$ to find the speed of the car before the brakes were applied. Round your answer to the nearest tenth.

Accident investigation The skid marks for a car involved in an accident measured 216 feet. Use the formula $s=\sqrt{24d}$ to find the speed of the car before the brakes were applied. Round your answer to the nearest tenth.

$72\phantom{\rule{0.2em}{0ex}}\text{feet}$

Accident investigation An accident investigator measured the skid marks of one of the vehicles involved in an accident. The length of the skid marks was 175 feet. Use the formula $s=\sqrt{24d}$ to find the speed of the vehicle before the brakes were applied. Round your answer to the nearest tenth.

Accident investigation An accident investigator measured the skid marks of one of the vehicles involved in an accident. The length of the skid marks was 117 feet. Use the formula $s=\sqrt{24d}$ to find the speed of the vehicle before the brakes were applied. Round your answer to the nearest tenth.

$53.0\phantom{\rule{0.2em}{0ex}}\text{feet}$

## Writing exercises

Explain why an equation of the form $\sqrt{x}+1=0$ has no solution.

1. Solve the equation $\sqrt{r+4}-r+2=0$ .
2. Explain why one of the “solutions” that was found was not actually a solution to the equation.

## Self check

After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section. After reviewing this checklist, what will you do to become confident for all objectives?

integer greater than 2 and less than 12
2 < x < 12
Felix
I'm guessing you are doing inequalities...
Felix
Actually, translating words into algebraic expressions / equations...
Felix
hi
Darianna
hello
Mister
He charges $125 per job. His monthly expenses are$1,600. How many jobs must he work in order to make a profit of at least $2,400? Alicia Reply at least 20 Ayla what are the steps? Alicia 6.4 jobs Grahame 32 Grahame 1600+2400= total amount with expenses. 4000/125= number of jobs needed to make that min profit of 2400. answer is 32 Orlando He must work 32 jobs to make a profit POP what is algebra Azhar Reply repeated addition and subtraction of the order of operations. i love algebra I'm obsessed. Shemiah hi Krekar One-fourth of the candies in a bag of M&M’s are red. If there are 23 red candies, how many candies are in the bag? Leanna Reply they are 92 candies in the bag POP rectangular field solutions Navin Reply What is this? Donna t muqtaar the proudact of 3x^3-5×^2+3 and 2x^2+5x-4 in z7[x]/ is anas Reply ? Choli a rock is thrown directly upward with an initial velocity of 96feet per second from a cliff 190 feet above a beach. The hight of tha rock above the beach after t second is given by the equation h=_16t^2+96t+190 Usman Stella bought a dinette set on sale for$725. The original price was $1,299. To the nearest tenth of a percent, what was the rate of discount? Manhwa Reply 44.19% Scott 40.22% Terence 44.2% Orlando I don't know Donna if you want the discounted price subtract$725 from $1299. then divide the answer by$1299. you get 0.4419... but as percent you get 44.19... but to the nearest tenth... round .19 to .2 and you get 44.2%
Orlando
you could also just divide $725/$1299 and then subtract it from 1. then you get the same answer.
Orlando
p mulripied-5 and add 30 to it
Tausif
Tausif
how
muqtaar
Can you explain further
p mulripied-5 and add to 30
Tausif
-5p+30?
Corey
p=-5+30
Jacob
How do you find divisible numbers without a calculator?
TAKE OFF THE LAST DIGIT AND MULTIPLY IT 9. SUBTRACT IT THE DIGITS YOU HAVE LEFT. IF THE ANSWER DIVIDES BY 13(OR IS ZERO), THEN YOUR ORIGINAL NUMBER WILL ALSO DIVIDE BY 13!IS DIVISIBLE BY 13
BAINAMA
When she graduates college, Linda will owe $43,000 in student loans. The interest rate on the federal loans is 4.5% and the rate on the private bank loans is 2%. The total interest she owes for one year was$1,585. What is the amount of each loan?
Sean took the bus from Seattle to Boise, a distance of 506 miles. If the trip took 7 2/3 hours, what was the speed of the bus?
66miles/hour
snigdha
How did you work it out?
Esther
s=mi/hr 2/3~0.67 s=506mi/7.67hr = ~66 mi/hr
Orlando
No; 65m/hr
albert
hello, I have algebra phobia. Subtracting negative numbers always seem to get me confused.
what do you need help in?
Felix
Heather
look at the numbers if they have different signs, it's like subtracting....but you keep the sign of the largest number...
Felix
for example.... -19 + 7.... different signs...subtract.... 12 keep the sign of the "largest" number 19 is bigger than 7.... 19 has the negative sign... Therefore, -12 is your answer...
Felix
—12
Thanks Felix.l also get confused with signs.
Esther
Thank you for this
Shatey
ty
Graham
think about it like you lost $19 (-19), then found$7(+7). Totally you lost just $12 (-12) Annushka I used to struggle a lot with negative numbers and math in general what I typically do is look at it in terms of money I have -$5 in my account I then take out 5 more dollars how much do I have in my account well-\$10 ... I also for a long time would draw it out on a number line to visualize it
Meg
practicing with smaller numbers to understand then working with larger numbers helps too and the song/rhyme same sign add and keep opposite signs subtract keep the sign of the bigger # then you'll be exact
Meg
hi
albert
Bruce drives his car for his job. The equation R=0.575m+42 models the relation between the amount in dollars, R, that he is reimbursed and the number of miles, m, he drives in one day. Find the amount Bruce is reimbursed on a day when he drives 220 miles
168.50=R
Heather
john is 5years older than wanjiru.the sum of their years is27years.what is the age of each
46
mustee
j 17 w 11
Joseph
john is 16. wanjiru is 11.
Felix
27-5=22 22÷2=11 11+5=16
Joyce By OpenStax By OpenStax By Saylor Foundation By OpenStax By Christine Zeelie By Jonathan Long By Katherina jennife... By OpenStax By OpenStax By Jonathan Long