Question

If one root of the equation x² + px +12 is 4, while the equation x² +px +q = 0 has equal roots, the value of q is 

A. 46/4 

B. 4/49 

C. 4 

D. none of these

Answer 1

Given 4 is the root of x² + px + 12 = 0 

= 16 + 4p + 12 = 0 

4p = - 28 

P = -7 

Given x² + px + q = 0 has equal roots, then discriminant is 0. 

D = b² – 4ac = 0 

p² – 4q = 0 

4q = 49 

q = \(\frac{49}{4}\).