Q.

If the roots of equation ax² + bx + c = 0, a ≠ 0 are real and equal, then which of the following relation is true

1 a = 2b²/c  
2 b² = 2ac  
3 ac = b²/4  
4 c = 4b²/a  

Ans.

(3)

Given equation is ax² + bx + c = 0, a ≠ 0.
For real and equal roots, D = 0.

⇒ b² − 4ac = 0 ⇒ b² = 4ac ⇒ b²/4 = ac