Question

If the equation 9y2 + 6ky + 4 = 0 has equal roots, then the value of k a) ±1 b) ±2 c) ±3 d) ±4 ​

Answer 1

Given:

• The equation 9y² + 6ky + 4= 0 has equal roots .

To find :

• The value of k.

Solution:

• As we know that , For equal roots :

• Discriminant must be equal to zero.

D = b²- 4ac = 0

Here ,

a= 9 , b = 6k , and c = 4 .

=> b²-4ac= 0

=> (6k)² - 4 (9)(4)=0

=> 36k² - 144=0

=> 36k²= 144

=> k²= 144/36

=> k²= 4

=> k = ±2.

Hence ,the option b is correct .

I hope it will help you.

Regards.