神马作文网化简化简并求值 x=2 y=90(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+.+(8x+y
来源：学生作业帮 编辑：神马作文网作业帮 分类：数学作业 时间：2024/11/10 22:34:57
化简
化简并求值 x=2 y=90
(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+.+(8x+y/8*9)
(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+....+(9x+y/8*9)
对不起 后面是9 ,打错了
化简并求值 x=2 y=90
(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+.+(8x+y/8*9)
(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+....+(9x+y/8*9)
对不起 后面是9 ,打错了
(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+.+(8x+y/8*9)
=(x+2x+3x+...+8x)+y[1+(1/2)+1/(2×3)+1/(3×4)+...+(1/(8×9)
=x(1+2+3+...+8)+y[1+(1/2)+(1/2-1/3)+(1/3-1/4)+.+
(1/8-1/9)]
=36x+y[1+1/2+1/2-1/9]
=36x+(17/9)y
x=2 y=90 时值=36×2+(17/9)×90=72+170=242
=(x+2x+3x+...+8x)+y[1+(1/2)+1/(2×3)+1/(3×4)+...+(1/(8×9)
=x(1+2+3+...+8)+y[1+(1/2)+(1/2-1/3)+(1/3-1/4)+.+
(1/8-1/9)]
=36x+y[1+1/2+1/2-1/9]
=36x+(17/9)y
x=2 y=90 时值=36×2+(17/9)×90=72+170=242
化简化简并求值 x=2 y=90(x+y)+(2x+y/2)+(3x+y/2*3)+(4x+y/3*4)+.+(8x+y
化简下列各式,并求值:3(x-y)²-7(x-y)+8(x-y)²+6(x-y) 其中x=2,y
化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1
初二化简求值题[（5x+2y)(3x+2y)+(x+2y)(x-2y)]/4x,其中x=2,y=3
先化简,再求值：[(x+y)(x-y)-(x-y)^2+2y(x-3y)]/(-4y),其中x=1,y=-2
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
化简求值：(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y),其中x=2,y=-1
化简求值:2(x-2y)^2-4(x-2y)+(x-2y)^2-3(x-2y),
(x+y)(x-2y)(x²-4y²) 其中x=8 y=-8 化简求值
化简求值(x+2y)^2-(2x+y)(2x-y)-5y(y-x) 其中 x=1/3 y= -1/2
化简求值:[(x+y)(x-y)-(x-y)²+2y(x-y)]÷4y,其中x=二分之一,y=2
化简求值(4x-3y)^2-(5x+y)^2-(3x+2y)(4y-3x),其中x1/3,y=6