Question

Solve using the square root method. x2 - 16 = 0
A.{-8, 8}
B.{-4, 4}
C.{8}
D.{4}

Answer 1

okay so first add 16 to both sides

Answer 2

what do you get?

Answer 3

x^2 = 16

\[x = \sqrt{16}\]

\[x = \pm ?\]

Answer 4

@ campbell_st x=4

Answer 5

correct!

Answer 6

its impoortant to remember tho what x^2 really means.

Answer 7

i know

Answer 8

so the answer would be d then thanks very much

Answer 9

and remember the are 2 solutions to this problem

Answer 10

nope
not d

Answer 11

Nah, don't forget x = ±2, not 2 itself alone!

Answer 12

check it out

Answer 13

x^2 = x * x = 16
"what times what equals 16?"

Answer 14

Sorry x = ±4, not 4 itself alone

Answer 15

well 4 times 4 equals 16

Answer 16

oh there are two so it would be b

Answer 17

but what about -4 times -4? does -4 times -4 equal 16?

Answer 18

correct!

Answer 19

but 8 * 8 doesn't equal 16 either...

Answer 20

nope 8 * 8 = 64

Answer 21

yes i know that ^

Answer 22

okay so we start with
x^2 -16 = 0

Answer 23

we are then allowed to add the same thing to both sides

Answer 24

+16 is a smart choice

Answer 25

so add 16 to the left side and add 16 to the right side

Answer 26

then we end up with
x^2 = 16

Answer 27

well x^2 just means x * x

Answer 28

so
x*x =16

Answer 29

or "what times what equals 16?"

Answer 30

4 * 4 = 16

Answer 31

-4 * -4 = ?

Answer 32

16 because a negative times a negative equals a positive

Answer 33

yes!

Answer 34

so we could plug 4 in for x and get 16 but we could also plug in -4!

Answer 35

ypu

Answer 36

so there are two numbers that work!

Answer 37

yup*

Answer 38

4 and -4 both work