Please help me with this question i don't get it

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Plz determine whether the polynomial is a difference of squares and if it is, factor it. y2 – 196 is a difference of squares: (y + 14)2 is a difference of squares: (y – 14)2 is a difference of squares: (y + 14)(y – 14) is not a difference of squares

Which graph has a rate of change of zero