Hello members,
I am working on my SAT practice and i came across this problem.
$\displaystyle x^-2=16$
I dont remember learning this. Any help would be appreciated. Thanks.
PS. That is supposed to be X to the -2 power.
Hello members,
I am working on my SAT practice and i came across this problem.
$\displaystyle x^-2=16$
I dont remember learning this. Any help would be appreciated. Thanks.
PS. That is supposed to be X to the -2 power.
Here is a quick way to get the answer on the SAT:
$\displaystyle x^{-2}=16$
Simply raise both sides to the reciprocal power:
$\displaystyle (x^{-2})^{-\frac{1}{2}}=16^{-\frac{1}{2}}=.25$
So grid in $\displaystyle .25$
Notes:
(1) To solve this you only need to type the following into your calculator: $\displaystyle 16^{-.5}$
(2) If this were a multiple choice question you could simply plug the answer choices in for x in the original question. You should almost always start with choice (C) when using this strategy. (Of course the solution I have given is better, but it requires some mathematical knowledge, whereas this one does not.)
(3) Note that this problem is incomplete as you have stated it since -.25 is also a solution. So either you haven't written the question precisely or this isn't an actual SAT practice problem. In any case, the solution to a grid-in can't be negative.
(4) The above posters have given a better solution to this problem, but on the SAT you don't generally want the most complete solution. You want to get the answer as quickly and efficiently as possible.