Question

30. If 8-4* -9.24 +1=0 then the value of x is (a) -1 (b) -2 (d) none of these

JEE/Engineering Exams

Maths

Solution

110

4.0 (1 ratings)

( 8 cdot 4^{x}-9 cdot 2^{x}+1=0 ) ut ( 2^{n}=t ) ( 8 z^{2}-9 z+1=0 ) ( 5 t^{2}-8 t-t+1=0 ) 2) 3) ( 8 t(t-1)-1(t-1)=0 ) ( Rightarrow quad t=1, quad 1 / 8 ) ( Rightarrow 2^{x}=1 quad ) or ( 2^{x}=1 / 8=2^{-3} ) ( therefore u=0,-3 ) -