1.

If `g(x)=x^2+x-2a n d1/2gof(x)=2x^2-5x+2,`then which is not a possible `f(x)?``2x-3`(b) `-2x+2``x-3`(d) None of theseA. `2x-3`B. `-2x+2`C. `x-3`D. None of these

Answer» Correct Answer - C
`(1)/(2)(gof)(x)=2x^(2)-5x+2`
` or (1)/(2)g[f(x)]=2x^(2)-5x+2`
` :. [{f(x)}^(2)+{f(x)}-2]=2[2x^(2)-5x+2]`
` or f(x)^(2)+f(x)-(4x^(2)-10x+6)=0`
` :. f(x)=(-1+-sqrt(1+4(4x^(2)-10x+6)))/(2)`
`=(-1+-sqrt((16x^(2)-40x+25)))/(2)=(-1+-(4x-5))/(2)`
`=2x-3 or -2x+2`


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