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求解答过程:先化简,再求值:[(x+2y)²-(x+y)(3x-y)-5y²]÷2x,其中...
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[(x-2y)^2+(x-2y)(x+2y)-2x(2x-y)]÷2x =[(x-2y)(x-2y+x+2y)-2x(2x-y)]÷2x =[2x(x-2y)-2x(2x-y)]÷2x =x-2y-(2x-y)=-x-y 题目中x+什么的绝对值?如果不懂,请追问,祝学习愉快!
先化简,再求值:[(x-2y)²-(x+y)(3x-y)-5y²]÷2x,其中x=-2,y=1 解:原式=[(x-2y)²-(x+y)(3x-y)-5y²]÷2x =(x^2-4xy+4y^2-3x^2+y^2-2xy-5y^2)÷2x =(-2x^2-6xy)÷2x =-x-3y =2-3 =-1 ...
(x-2y)(x+2y)+(x-2y)²=x²-4y²+(x²-4xy+4y²)=2x²-4xy 本题没有告诉x和y的值,无法计算,只能将多项式化简后,再代入x和y的值计算即可。
原式=4x 2 +4xy+y 2 -4x 2 +y 2 -4xy=2y 2 , 当y=-1时,原式=2.
(x+y)(x-y)+(x-y)方-(6x方y-2xy方)÷2y =(x-y)(x+y+x-y) - 2xy(3x-y)÷(2y)=2x(x-y) - x(3x-y)=x(2x-2y -3x+y)=x(-x-y)=-x(x+y)已知x=-2,y=3分之1,那么:原式=-x(x+y)=-(-2)*(-2+ 3分之1)=2*(-3分之5)=-3分之10 ...
(1)原式=[x3y2-x2y-x2y+x3y2]?x2y=[2x3y2-2x2y]?x2y=2x5y3-x4y2;(2)原式=x2+4x+4-4x2-1-4x-4x2=x2+3,当x=12时,原式=134.
∵|x-3a|≥0,(y+5)^2≥0 又:|x-3a|+(y+5)^2=0 ∴|x-3a|=(y+5)^2=0 ∴x=3a,y=-5 a=B-2A= 4x^2-6xy+2y^2-3x-y -2(2x^2-3xy+y^2-x+2y )= 4x^2-6xy+2y^2-3x-y -4x^2+6xy-2y^2+2x-4y = -x-5y x=3a=-3x-15y x=-15y/2=-15*(-5)/2=75...
(x+y)(x-y)+(x^2-2xy+y^2)-(x^2y)^3÷(x^2y)^2 =x²-y²+x²-2xy+y²-x²y =2x²-2xy-x²y 当x=1,y=2时 原式=2-4-2 =-4
[(2x+y) 2 -(2x-y)(2x+y)]÷(2y),=[4x 2 +4xy+y 2 -4x 2 +y 2 ]÷(2y),=(4xy+2y 2 )÷(2y),=2x+y,当x=2,y=-1时,原式=2×2+(-1)=3.