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If 2 is a root of the equation x2−px+6=0x^2 -px +6 = 0x2−px+6=0​ and the quadratic equation x2+2px+q=0x^2 +2px + q = 0 x2+2px+q=0 has equal roots
Question

If 2 is a root of the equation x2px+6=0x^2 -px +6 = 0​ and the quadratic equation x2+2px+q=0x^2 +2px + q = 0 has equal roots, then the value of q is:

A.

25

B.

36

C.

12

D.

16

Correct option is A

Given:

Roots of quadratic equation x2px+6=0x^2 -px +6 = 0​ is 2

Quadratic equation x2+2px+q=0x^2 +2px + q = 0​ has equal roots

Formula Used:

For a quadratic equation ax2+bx+c=0ax^2 + bx + c = 0 ​​

If roots are equal then discriminant D=b24ac=0D = b^2 - 4ac = 0​​

Solution:

Putting the value of x in x2px+6=0x^2 -px +6 = 0​​

(2)2p(2)+6=0(2)^2 -p(2) +6 =0​​

4 - 2p + 6 = 0

2p =10

p = 5

x2+2px+q=0x^2 +2px + q=0 ​has equal roots

Then D =(2p)24(1)(q)=0= (2p)^2 - 4(1)(q)=0​​

(10)24q=0(10)^2- 4q=0​​

4q = 100

q= 25

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