Find the term in the expansion of (x-(2/x^2))^14 which is of the form constant/x.
The Attempt at a Solution
I have worked out the general expression. (14|r) x^14-r * (-2/x^2)^r
However I can only work out this problem by trial and error. I know that in this case r=5, however I didn't solve it by equation. What equation would I need to construct to get this answer r=5? I know that for the answer to be constant/x the power of x on the denominator can only be 1 greater than the power of x on the numerator.
How do I construct an equation with r to solve this?