Q11 / 82 · NTA Abhyas (JEE Main) 2020 · Mathematics · Quadratic Equation

Let fx=x2+2px+2q2 and gx=-x2-2qx+p2 (where q≠0). If x∈R and the the minimum value of fx is equal to the maximum value of gx, then the value of p2q2 is equal to 

Correct answer: 0.5

Solution

Since the minimum/maximum value of a quadratic expression ax2+bx+c is given by 4bc-b24a

So, fmin=2q2-p2, gmin=p2+q2
Now, 2q2-p2=p2+q2⇒q2=2p2

Hence, p2q2=12=0.5

Hence, the correct answer is 0.5.

More Quadratic Equation Questions