Question

find a such that 9x²+2x+a is a perfect square​

Answer 1

let 9x^2+2x+a=0

now put the value of x=-1 in equation

9(-1)^2+2(-1)+a=0

9+(-2)+a=0

7+a=0

a=-7

so x+1 is perfect square of this equation is that answer is correct

Answer 2

9x² +2x+a = ((3x) + √a)²

=9x² + a+ 6x√a

comparing

2x= 6x√a

1/3=√a

squaring both sides

a= 1/9