每项的系数是多少:-1/8(系数:-1/8)-a^2h(系数:-1)+3π(系数:3π); 注:π是3.14
简化求值:1/2x+(-3/2x+1/3y^2)-(2x-2/3y^2),其中x=-1/3,y=2/3
原式=(1/2x-3/2x-2x)+(1/3y^2+2/3y^2)
=(-3x)+y^2
=-3*(-1/3)+(2/3)^2
=1+4/9
=13/9
x(x+2y)-(x+1)^2+2x ,其中x=1/25,y=-25
原式=x^2+2xy-(x^2+2x+1)+2x
=(x^2-x^2)+(2x-2x)+2xy-1
=2xy+1
=2*1/25*(-25)+1
=-2+1
=-1