Question

Factor 16x^2 + 49. Check your work.

Answer 1

This is what i have so far:

Answer 2

16x2 + 49 = 16x2 – (-49) = (4x+7i)(4x-7i)

Answer 3

but when I checked my work, the result was 16x^2 - 49... so is that still right?

Answer 4

youre doing it right, your checkin is wrong. i x i = -1

Answer 5

so I just substitute all the i's with -1's and then multiply?

Answer 6

no
i into i is -1

Answer 7

huh?

Answer 8

what do u mean "into"?

Answer 9

i multiplied by i

Answer 10

so i fix the last part right? -49i^2

Answer 11

yes

- 49i^2 = -49 x -1
=49

Answer 12

ok so,

Answer 13

16x^2 +28x -28x +49i^2
16x^2 + 49i^2

Answer 14

bingo!

Answer 15

oh and i have one more

Answer 16

x^2 + 64

Answer 17

this is what i got:

Answer 18

x^2 – (-64)
(x+ 8i)(x- 8i)

Answer 19

so now i have to check it

Answer 20

so it's exactly the same right?

Answer 21

x^2 - 64i^2

Answer 22

get it?

Answer 23

yes

Answer 24

thanks

Answer 25

wait so that's what u get when u check it?

Answer 26

so its:
x^2 – 64i^2
x^2 – 64(-1)^2
x^2 +64

Answer 27

Yup

Answer 28

ok thanks

Answer 29

no prob