Ques. 1JEE Main 2024, 4 April (Morning Shift)
Let the sum of the maximum and the minimum values of the function f(x)= 2x2-3x+82x2+3x+8 be mn, where (m, n)=1. Then m+n is equal to :
- 217
- 182
- 201
- 195
Answer
(3) 201
Solution
Let y= 2x2-3x+82x2+3x+8
(denominator >0 for all real x, D=9-64<0)
(2y-2)x2+(3y+3)x+(8y-8)=0
x is real D 0:
(3y+3)2-4(2y-2)(8y-8) 0
9(y+1)2-64(y-1)2 0
(11y-5)(11-5y) 0 511 y 115
(y= 511 at x=2, y= 115 at x=-2)
mn= 511+ 115= 14655 m+n=146+55=201
Answer: (3)