Question

If the equation 9 x ^2 + 12kx + 8 =0 has equal roots, then the value of k is
Answer is
± 2
± 1
± 3
±√2

Answer 1

Answer:

option D

+/- root 2

D =0

b²=4ac

Answer 2

Answer:

± √2

Step-by-step explanation:

Given: Polynomial = 9 x ^2 + 12kx + 8 = 0

Always remember,

For equal roots, for ur convenience, u can apply the formula

b^2 = 4 ac

So here b = 12 k , a = 9 and c = 8

⇒b^2 = 4 ac

⇒( 12k ) ^2 = 4 ( 9 ) ( 8 )

⇒144 k ^2 = 288

⇒k^2 = 288 / 144

⇒k^2 = 2

⇒k =  ± √2                    [Transporting square root on right hand side