metallicafan wrote:

A fast way to solve this question? I solved it, but it took me more than 2 min :s.

What is the value of y^3 - t^3?

(1) y - t = 3

(2) y^2 - t^2 = 21

I spent a lot of time in solving the equations with the possible values of y and t.

Source: gmathacks.com

(1) - (y-t) = 3 ----> Y & t can be anything -Insufficient

(2) (y+t)(y-t) = 3 x 7 ----> (y+t) can be 3 or 7 -----> i.e. y will be 5 for sure but t can be 2 or -2 ----> Insufficient

(1+2) (y+t)= 7 because (y-t) = 3----> y = 5 & t=2--->Sufficient

Hope it helps.

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