Question

(x-1).(x+1)+3.(x+1).(x-1)+3.(x-1)+1

Answer 1

(x-1)(x+1)+3(x+1)(x-1)+3(x-1)+1=
x²-1+3(x²-1)+3(x-1)+1=
x²-1+3x²-3+3x-3+1=
x²+3x²+3x-1+1-3=
4x²+3x-3