Ques. 1JEE Main 2024, 27 January (Morning Shift)
If a= x 0 1+ 1+x4- 2x4 and b= x 0 2x 2- 1+ x, then the value of ab3 is :
- 36
- 25
- 32
- 30
Answer
(3) 32
Solution
Rationalise twice:
a= x 0 1+x4-1x4 ( 1+ 1+x4+ 2 )
= x 0 1 ( 1+ 1+x4+ 2 ) ( 1+x4+1 )
= 12 2 2= 14 2
b= x 0 2x ( 2+ 1+ x )1- x
2x=(1- x)(1+ x)
b= x 0(1+ x) ( 2+ 1+ x )
=2 2 2=4 2
ab3= (4 2)34 2=(4 2)2=32
Answer: (3)