Question

sabendo que f(x)=2x-1 e f(x)=21, entao o valor de x é??

Answer 1

$f(x)=2x-1 \\ 21=2x-1 \\ -2x=-21-1 \\ x= \frac{22}{2} \\ x=11$

Answer 2

22=2x-1
22+1=2x
22=2x
x=22/2
x=11