Question

Solve 4r2 – 9 = 91.

A.
{± 3}

B.
{± 4}

C.
{± 5}

D.
{±6}

Answer 1

add 9 to both sides
divide both sides by 4
take the square root of each side

Answer 2

4r^2=100

Answer 3

@Vocaloid

Answer 4

alright, so you added 9 to each side
what's the next step?

Answer 5

r^2=25

Answer 6

good, what's the next step?

Answer 7

r^2=5

Answer 8

@Vocaloid

Answer 9

not quite, check the left side

Answer 10

im not sure what to do to the left side!

Answer 11

hint: the square root of a^2 = a
so what is the square root of r^2?

Answer 12

r=5

Answer 13

you're very close! when we take the square root of something, the answer can be either positive or negative, which is why