图
(1)f(x+1)=5x-1=5(x+1)-6→f(x)=5x-6(2)f(x-2)=3x-1=3(x-2)+5→f(x)=3x+5(3)f(x-1)=5x^2-x=5(x-1)^2+9x-6=5(x-1)^2+9(x-1)+3→f(x)=5x^2+9x+3
