Ques. 1JEE Main 2024, 27 January (Morning Shift)
Let the set of all a such that the equation 2x+a x=2a-7 has a solution be [p, q] and r= 9 - 27 - 1 63 + 81 , then pqr is equal to .
Answer
48
Solution
1-2 2x+a x=2a-7 ⇒ 2( 2x-4)-a( x-2)=0
⇒ ( x-2)(2 x+4-a)=0
∵ x 2 ⇒ a=2 x+4 [2, 6] ⇒ p=2, q=6
1 63 = 27 , 81 = 9
⇒ r=( 9 + 9 )-( 27 + 27 )
∵ + = 2 2
⇒ r= 2 18 - 2 54 = 8 5-1- 8 5+1= 164=4
∴ pqr=2 6 4=48
Answer: 48