Anybody up to help me with my math?

Describe the 2 algebraic methods you can use to find the zeros of the function f(t)=-16t^2+400.

The lengths of two sides of a right triangle are given. find the length of the third side. round to the nearest tenth if necessary. a) y = 12/5x + 39/5 b) y = 5/12x + 5/39 c) y = 12/5x - 39/5 d) y = 5/12x - 5/39

Can someone tell me if this is perpendicular? !