If 25x²+k+9 is a perfect square find k

Answer 1

well, 25=5^2 and 9=3^2, so try

(5x+3)^2 = ?

Note that you will get two answers.

Answer 2

(b/2)^ 2=ac
so k^2/2=25X9
=225
225X4=900
k^2=900
so k=30