1.

show that the function `f : R to R : f (x) =2x +3` is invertible and find `f^(-1)`

Answer» Correct Answer - `f^(-1) (y)= (1)/(2) (y-3)`
`f(x_(1)) =f(x_(2)) rArr 2x_(1) +3 =2x_(2)+3 rArr 2x_(1)=2x_(2) rArr x_(1)=x_(2)`
`:. ` f is one-one
If `y in R` then there exists `x=(y-3)/(2) in R` such that
`f(x)= f((y-3)/(2)) ={2.((y-3))/(2)+3}=y`
`:. ` f is onto.
`y =f(x) rArr y =2x+3`
`rArr x=(1)/(2) (y-3) rArr f^(-1) (y)=(1)/(2) (y-3)`


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