Question

Find the value of k for which the equation ax^2 +3kx+4 = 0 has real roots

Answer 1

if the equation has real roots 
discriminant D =b²-4ac ≥0
compare given equation with ax²+bx+c =0
a = a, b =3k,c=4

(3k)²-4*a*4≥0

(3k)² ≥16 a

k ≥ 4√a/3