1)x^2+2x-3(x^2-3分之2x)其中x=2分之1
=x^2+2x-3x^2+2x
=-x^2+4x
=-1/4+2
=7/4
2)(4x-2y)-[-2(x-y)+(2x+y)]-4x其中x=0,y=-3
=4x-2y+2(x-y)-(2x+y)-4x
=-2y+2x-2y-2x-y
=-5y
=15