1.

If 2 is a root of the equation x2 + ax + 12 = 0 and the quadratic equation x2 + ax + q = 0 has equal roots, then qA. 12B. 8C. 20D. 16

Answer»

The given equation x2 + ax + 12 = 0 has a root = 2 

So it will satisfy the equation 

4 + 2a + 12 = 0 

2a + 16 = 0 

a = – 8 

Putting value of a in second equation, it becomes 

x2 + ax + q = 0 

x2 – 8x + q = 0 

Roots are equal so d = 0 

⇒ b2 – 4ac = 0 

⇒ 64 – 4q = 0 

⇒ q = 64/4 

⇒ q = 16



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