计算:(2x+y+z)(2x-y-1)

计算：3x-2y- [-4x+(z+3y)] (y-x)/(x+z-2y)(x+y-2z)+(z-y)(x-y)/(x+y-2z)(y+z-2x)+(x-z)(y-z x,y,z正整数 x>y>z证明 x^2x +y^2y+z^2z>x^(y+z)*y^(x+z)*z^(x+y) 化简(y-x)(z-x)/(x-2y+z)(x+y-2z)+（z-y)(x-y)/(x-2z+y)(y+z-2x)+(x 已知 x,y,z都是正实数,且 x+y+z=xyz 证明 (y+x)/z+(y+z)/x+(z+x)/y≥2(1/x+1 计算 (1)（-3x³y/2z²)² 计算（x+2y-3z)的平方+（x-2y+3z)(x+2y-3z) (x+2y+3z)-(3x+2y-z)+(2x-3y+4z) 用直式计算 计算:1:(2a-3b-c)^2 2:(3y-y-1)(y-3x-1) 3:(2x+y-z)(z-2x+y) 数学题三道计算(X-2Y+Z)(X+2Y-Z)[(1/4)X-(2/5)Y]^2*[(1/4)X+(2/5)Y]^2[( (x-2y+z)(x+y-2z)分之（y-x)(z-x) + (x+y-2z)(y+z-2x)分之(z-y)(x-y) 解乘法公式计算1·（x+y+2z）（x-y-2z）2·（x+2y-z）^2