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化简求值:(x+2y) 2 %(2x+y) 2 ,其中x=%2,y=1

原式=(x 2 +4xy+4y 2 )-(4x 2 +4xy+y 2 )=x 2 +4xy+4y 2 -4x 2 -4xy-y 2 =-3x 2 +3y 2 ,当x=-2,y=1时,原式=-3×(-2) 2 +3×1 2 =-3×4+3=-12+3=-9.

原式=x?yx+2y?(x+2y)2(x+y)(x?y)-2=x+2yx+y-2=x+2y?2(x+y)x+y=-xx+y,当x=1+2,y=1-2时,原式=-1+22.

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解:原式 当x=3,y=-1.5时,原式= 4.5

原式=2(4x²+25y²)-(4x²-25y²) =4x²+75y² =4*4+75*1/25 =16+3 =19

(x-4y-x-16y-8xy)÷4y=(-8xy-20y)÷4y=-(2x+5y)=-(-10+10)=0

化简:6x²+2y-2x²+y 4x²+3y 带入x y 的值 等于 -2

(x+2y)²-(x+y)(x-y) =x²+4xy+4y²-x²+y² =4xy+5y² =4x(-2)x(1/2)+5x(1/2)² =-4+5/4 =-11/4

[(y-2x)(-2x-y)-4(x-2y)²]÷3y =[4x^2-y^2-4x^2+16xy-16y^2]/3y =[16xy-17y^2]/3y =16x/3-17y/3 希望你能看懂,祝你学习进步

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