(x+4)(x-2)(x-4)
=(x-2)(x²-16)
x=-1代入
-3×(1-16)
=-3×(-15)
=45
x(x+2y)-(x+1)的二次方+2x
=x²+2xy-x²-2x-1+2x
=2xy-1
x=25分之1 y=-25代入得
2*(1/25)*(-25)-1
=-2-1
=-3