Just finished my math test on got 21/22 but i dont understand why i got the 1 wrong. It says;

What makes this a true statement 9^2= ?

I answered -1/18 because i had no idea and thought the answer was 0.09. It says the answer is 1/18, why is this? I will medal the best answer! Just please HELP!

Question

Just finished my math test on got 21/22 but i dont understand why i got the 1 wrong.  It says;

What makes this a true statement 9^2= ?

I answered -1/18 because i had no idea and thought the answer was 0.09. It says the answer is 1/18, why is this? I will medal the best answer! Just please HELP!

anonymous · Answer

@e.mccormick @love10129151 can you help?

anonymous · Answer

Are you sure it said: $$9^2=?$$Because $9^2=81.$

anonymous · Answer

it said 9$$^{-2}$$ sorry typo

anonymous · Answer

$$*9^{-2}$$

anonymous · Answer

Ah, ok. Use this rule: $$a^{-k}=\frac{1}{a^k}.$$

anonymous · Answer

So $$9^{-2}=\frac{1}{9^2}=\frac{1}{81}$$

e.mccormick · Answer

yah, as nerdguy2535 pointed out, it looks like you just transposed the numbers in the answer.

e.mccormick · Answer

Or perhaps that is another typo and the issue is the - ?

anonymous · Answer

no i thought the answer was actually 0.09 scientific notation. @nerdguy2535 is right, thanks though!

e.mccormick · Answer

Kk.  Long as you understand what nerdguy2535 did you should be able to answer these.  It is a basic thing of how negative exponents work.

triciaal · Answer

square of a number is always positive 
when you take the square root 2 solutions

triciaal · Answer

What makes this a true statement 9^2= ?
what were the choices?