先化简再求值1 x 1-3-x x的平方-6x 9
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原式=4−xx−2÷x2−16x−2=4−xx−2•x−2(x+4(x−4)=-1x+4,当x=3−4时,原式=-13−4+4=-33.
x1+x2=-5,x1x2=-31)|x1-x2|^2=(x1+x2)^2-4x1x2=25+12=37|x1-x2|=√372)1/x1^2+1/x2^2=(x1^2+x2^2)/(x1x2)^2=
(xx+1+1)÷(1−3x21−x2)•1x−1=x+x+1x+1÷1−x2−3x21−x2•1x−1=2x+1x+1÷(1+2x)(1−2x)(1+x)(1−x)•1x−1=1−x1−2x•1x−
(xx)/(xxxx+xx+1)=x^2/(x^4+x^2+1)=1/x^2+1+x^2=x^2+1/x^2+2-1=(x+1/x)^2-1=3^2-1=8
原式=[3x(x−2)(x+2)(x−2)−x(x+2)(x+2)(x−2)]×(x+2)(x−2)2x=2x(x−4)(x+2)(x−2)×(x+2)(x−2)2x=x-4,当x=4−5时,原式=4
由题意x1^2+3x1+1=0x1^2=-1-3x1原式=x1*x1^2+8x2+20=x1(-1-3x1)+8x2+20=-3x1^2-x1+8x2+20=-3(-1-3x1)-x1+8x2+20=
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方程3x²-4x=-1可化为:3x²-4x+1=0由根与系数的关系,有x1+x2=4/3,x1x2=1/3∴x2/x1+x1/x2=(x1²+x2²)/(x1x
原式=x(x−1)2•(x+1)(x−1)x(x+1)=1x−1,当x=2+1时,原式=12+1−1=22.
原式=[x2x(x−1)-1x(x−1)]×1x+1=(x−1)(x+1)x(x−1)×1x+1=1x,当x=2时,原式=12=22.
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1x1\3=1/2*(1/1-1/3)2x1\4=1/2*(1/2-1/4).1x1\3+2x1\4+3x1\5+.+2006x1\2008=1/2(1/1-1/3+1/2-1/4+1/3-1/5+.
1.已知x+y=5,2x-y=1,化简xy(x+y的平方)-y的平方(xy-x)+2x(x-y的平方),并求它们的值.3.3ab-4ab+8ab-7ab+ab=______.4.7x-(5x-5y)-
由韦达定理有x1+x2=3/2x1*x2=-1/2x1^3x2+x1x2^3=x1x2(x1^2+x2^2)=x1x2[(x1+x2)^2-2x1x2]=-1/2*(9/4+1)=-13/8
原式=(xx+1+1x−1)×4xx 2+1=x 2+1(x+1)(x−1)×4xx 2+1=4x(x+1)(x−1),由x2-2x-1=0,得2x=x2-1=(x+1)
x^2+x-x^2-y=3x-y=3(x-y)^2=9x^2+y^2-2xy=9(x^2+y^2)/2-xy=9/2
原式=3x(x+1)−x(x−1)x2−1•x2−1x=3x2+3x−x2+xx=2x2+4xx=2x+4,当x=2-2时,原式=2×(2−2)+4=22.
X1X2=1X1+X2=3x1^2-4x1-x2=x1^2-4x1-(3-x1)=x1^2-3x1-3∵x1,x2是方程x^2-3x+1=0的解∴x1^2-3x1+1-4=-4
x(x+1)-(xx+y)=-3x^2+x-x^2-y=-3x-y=-3(xx+yy)/2-xy=(x^2+y^2-2xy)/2=(x-y)^2/2=(-3)^2/2=9/2再问:是对的吧!再答:当然