Question

The roots of the quadratic equation 9y²+my+36=0 are real and equal, find m.​

Answer 1

Answer:

When roots are real and equal,

D = 0

According to the question,

$a = 9$

$b = m$

$c = 36$

Using discriminant formula,

$\bold{ d = {b}^{2} - 4ac}$

Substitute value of a, b, c

$\implies \: 0 = {m}^{2} - (4 \times 9 \times 36)$

$\implies \: 0 = {m}^{2} - {36}^{2}$

$\implies \: {m}^{2} = {36}^{2}$

Taking square root on both sides,

$\implies {\boxed{ \large \: m = 6}}$