化简求值 (3x-1)的平方(2x-3)
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=X^2-8x=100-80=20给个最佳啊
原式=(x³-4x)-(x³-3x²+2x-3x²-9x+6)-(2x²-4x)=x³-4x-x³+7x-6-2x²+4
-5(xy-6x的平方+7y)+3(2xy-x的平方+2y)=-5xy+30x^2-35y+6xy-3x^2+6y=27x^2-29y+xy=27*(1/2)^2-29*(-1)+1/2*(-1)=2
(3x-y)的平方-(2x+y)的平方-5x(x-y)=(3x-y+2x+y)(3x-y-2x-y)-5x(x-y)=5x(x-2y)-5x(x-y)=5x(x-2y-x+y)=5x*(-y)=-5x
2x²-[-3(-1/3x²-2/3xy)-2y²]-2(x²-xy+2y²)=2x²-[x²+2xy-2y²]-2x&
2(3x的平方+y)-(2x的平方-y)=6x²+2y-2x²+y=4x²+3y=4*(1/2)²+3*(-1)=1-3=-2
[(x+2y)^2-(x+y)(3x-y)-5y^2]/2x=(x^2+4xy+4y^2-3x^2-3xy+xy+y^2-5y^2)/2x=(-2x^2+2xy)/2x=-x+y=2+1/2=二分之五
x(x+2y)-(x+1)+2x=x+2xy-x-2x-1+2x=2xy-1因为x=1/25,y=-25原式=2*1/25*(-25)-1=-3
2(x立方+4x平方-1)-(x-3x平方+2x立方)=2X³+8X²-2-X+3X²-2X³=11X²-X-2当X=-3时,原式=11*(-3)
解1原式=9X+6X^2-3X+2X^2=8X^2+6X将X=-2代入,得8*4-6*2=32-12=20解2原式=a^2b-ab-ab^2-ab+2ab^2+2ab=a^b+ab^2将a=-1/2b
(3x/x+1-x/x-1)+x-2/x的平方-1=(3x(x-1)-x(x+1))/(x+1)(x-1)+x-2/x^2-1=(3x^2-3x-x^2-x+x-2)/(x^2-1)=(2x^2-3x
(4x²-3x)+(2+4x-x²)-(2x²+x+1)先去括号;4x²-3x+2+4x-x²-2x²-x-1合并同类项x²+1代
1/3x的平方(3不平方)+3/4x=1/3(x+9/8)^2-27/64当x=-9/8时,有最小值-27/64
2(x²y+xy)-3(x²y+xy)-4x²y=-(x²y+xy)-4x²y=-5x²y-xy=-xy(5x+1)=1×2(-5+1)=-
-3(2x^2-xy-6)貌似这个式子化不化简没有关系呢原式=-3(2*1^2-1*2-6)=-3(4-2-6)=12
2(x的平方+xy)-3(xy的平方-xy)-4x的平方y=2x²+2xy-3xy²+3xy-4x²y=2x²+5xy-xy(3y+4x)
原式=(x+y)(x-y)-(x-y)=(x-y)(x+y-1)(2b-a+m)/2-(1/2b-a+m)=1两边乘22b-a+m-b+2a-2m=2m=b+a-2=-1+3-2=0
【(x的平方+5x+6)/(x+3)/(x平方-4)/(x-3)】-1=【(x+2)(x+3)/(x+3)/(x平方-4)/(x-3)】-1=【(x+2)/(x+2)(x-2)/(x-3)】-1=【1