Question

Evaluate 1/2a^-4b^2 for a=-2 and b=4
2
1/2
3
4
I got 128. I have a strange feeling that's wrong. So...yeah can someone please explain this?

Answer 1

can you show how you got 128 ?
then i'll tell you in which step, there was error.

Answer 2

I did (-2)^-4 and got 32 then 4^2 and got 16. Then I multiplied those two numbers then divided by 2.

Answer 3

(-2)^-4 = 1/ (-2)^4 = 1/16
did you get how ?

Answer 4

\[a^{-n} = 1/a^n\]

Answer 5

No. I don't understand how you got that. Whats the first step?

Answer 6

\[(-2)^{-4} = \dfrac{1}{(-2)^4 }\\as, (a)^{-n} = \dfrac{1}{(a)^n }\]
got this ?

Answer 7

Oh! yeah I forgot you had to do that fraction thing.

Answer 8

\[(-2)^4=[(-2)^2]^2 = 4^2=16\]
\[(-2)^2=(-2)(-2)=4\]

Answer 9

so, now try again, you'll get it :)

Answer 10

Do you have to do the fraction thing for b?

Answer 11

no, b^2 = 4^2 = 16

Answer 12

Ok when you do the fraction thing do you multiple the two numbers and then put 1 over fraction? 1/32 or 1/(-2)^-4

Answer 13

like 1/2x1/(-2)-4x16

Answer 14

i got 1/2

Answer 15

1/2 is correct :)