1.

If `1,log_9(3^(1-x)+2), log_3(4*3^x-1)` are in A.P then x equals toA. `log_(4)3`B. `log_(3)4`C. `1-log_(3)4`D. `log_(3)0.25`

Answer» Correct Answer - C
Since 1, `log_(9)(3^(1-x)+2)andlog_(3)(4.3^(x)-1)` are in A.P
`:." "2log_(9)(3^(1-x)+2)=1+log_(3)(4.3^(x)-1)`
`rArr" "2log_(3)2(3^(1-x)+2)=log_(3)3+log_(3)(4.3^(x)-1)`
`rArr" "(2)/(2)log_(3)(3^(1-x)+2)=log_(3){(4.3^(x)-1)}`
`rArr" "(3^(1-x)+2)=3.(4.3^(x)-1)`
`rArr" "(3)/(y)+2=12y-3,"where "y=3^(x)`
`rArr" "12y^(2)-5y-3=0`
`rArr" "(3y+1)(4y-3)=0`
`rArr" "y=33//4" "[becausey=3^(x)gt0]`
`rArr" "3^(x)=(3)/(4)`
`rArr" "x=log_(3)(3//4)=log_(3)3-log_(3)4rArrx=1-log_(3)4`


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