Răspuns :
f(x+1)=3(x+1)-2
=3x+3-2
=3x+1
f(x-2)=3(x-2)-2
=3x-6-2
=3x-8
3x+1+3x-8=3x-2+4
6x-7=3x+2
3x=9
x=3
=3x+3-2
=3x+1
f(x-2)=3(x-2)-2
=3x-6-2
=3x-8
3x+1+3x-8=3x-2+4
6x-7=3x+2
3x=9
x=3