If the function `f:(1,)vec(1,oo)` is defined by `f(x)=2^(x(x-1)),t h e nf^(-1)(x)` is `(1/2)^(x(x-1))` (b) `1/2(1+sqrt(1+4(log)_2x))` `1/2(1-sqrt(1+(log)_2x)` (d) not defined

Explanation

`f(x)=2^(x(x+1)), i.e., y=2^(x(x+1))`


`⇒log_2​y=x(x−1)=x_2−x`


`⇒x_2−x−log_2​y=0`


`⇒x=(1±sqrt(1+4log_2​y))/2`


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