Maths P1.. HELP needed!!

[ashutoshamatya]

‎5. The function f i s defined by f:x --> ax+b, for x E R, where a and b are constants. It is given that f(2)=1 and f(5)=7.
(i) Find the values of a and b.
(ii) Solve the equation ff(x)=0

I did the first part but got confused in the second.. Plz help me out!!

 

[ashutoshamatya]

i got it..

since frm the 1st part
a = 2
and b = -3

ff(x) = 0
f(2x-3) = 0
2(2x-3)-3 = 0
4x-9 =0