let m and b be real numbers and let the function f be defined by

If f is both continuous and differentiable at x=1, then

m=?

b=?

my steps

-substitute for x=1

-combine like terms

-rearrange for m

-substitute back in

3+3b=(3+2b)+b

3+3b=3+3b

-this is where i am lost i dont even have a variable when I solve...

what did I do wrong?

All help is appreciated.