求值:(1)若a-b=2 ab=1 求a2+b2的值 (2)若x+y+z=3 xy+yz+zx=2 求x2+y2+z2(3)若(x-y)2=a (x+y)2=b 求[(x-y)5]*[ (x+y)7]*(y2-x2)(4)若x-y=4 x2+y2=5 求x3-y3
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求值:(1)若a-b=2 ab=1 求a2+b2的值 (2)若x+y+z=3 xy+yz+zx=2 求x2+y2+z2(3)若(x-y)2=a (x+y)2=b 求[(x-y)5]*[ (x+y)7]*(y2-x2)(4)若x-y=4 x2+y2=5 求x3-y3
求值:(1)若a-b=2 ab=1 求a2+b2的值 (2)若x+y+z=3 xy+yz+zx=2 求x2+y2+z2
(3)若(x-y)2=a (x+y)2=b 求[(x-y)5]*[ (x+y)7]*(y2-x2)
(4)若x-y=4 x2+y2=5 求x3-y3
求值:(1)若a-b=2 ab=1 求a2+b2的值 (2)若x+y+z=3 xy+yz+zx=2 求x2+y2+z2(3)若(x-y)2=a (x+y)2=b 求[(x-y)5]*[ (x+y)7]*(y2-x2)(4)若x-y=4 x2+y2=5 求x3-y3
(1)、因为:a-b=2 ,ab=1,所以:a^2+b^2=(a-b)^2+2ab=2^2+1=5;
(2)、因为:x+y+z=3 ,xy+yz+zx=2,所以:
x^2+y^2+z^2=(x+y+z)^2-2(xy+yz+zx)=3^2-2*2=5;
(3)、因为:(x-y)^2=a ,(x+y)^2=b,所以:
[(x-y)^5]*[ (x+y)^7]*(y2-x2)=[(x-y)^5]*[ (x+y)^7]*(y+x)(y-x)
=-(x-y)^6(x+y)^8
=-[(x-y)^2]^3[(x+y)^2]^4
=-a^3b^4
(4)、因为:x-y=4 ,x^2+y^2=5,所以:(x-y)^2=x^2+2xy+y^2=4 ^2,即:xy=11/2
所以:x^3-y^3=(x-y)(x^2+xy+y^2)=4*(5+11/2)=20+22=42.
1、a²+b²=a²-2ab+b²+2ab=(a-b)²+2ab=4-2=2
2、x²+y²+z²=x²+y²+z²+2xy+2xz+2yz-2(xy+xz+yz)=(x+y+z)²-2(xy+xz+yz)=9-4=5
3、(x-y)^5×(x+y)^7×(y-x...
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1、a²+b²=a²-2ab+b²+2ab=(a-b)²+2ab=4-2=2
2、x²+y²+z²=x²+y²+z²+2xy+2xz+2yz-2(xy+xz+yz)=(x+y+z)²-2(xy+xz+yz)=9-4=5
3、(x-y)^5×(x+y)^7×(y-x)(y+x)
=-(x-y)^6×(x+y)^8
=-a^3×b^4
4、x²+y²=x²-2xy+y²+2xy=(x-y)²+2xy=16-2xy=5
xy=11/2
x³-y³=(x-y)(x²+xy+y²)=4(5+11/2)=20+22=42
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(1).a-b=2那么a=2+b ab=1那么b(2+b)=1 (b+1)^2=2 b=-1+根号2 或b=-1-根号2
(2)(X+Y+Z)^2=X2+Y2+Z2+2XY+2XZ+2YZ=9 那么X2+Y2+Z2=9-4=5
(3)Y2-X2=-(X-Y)(X+Y)那么原式等于-(x-y)6(x+y)8=-a3*b4
(...
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(1).a-b=2那么a=2+b ab=1那么b(2+b)=1 (b+1)^2=2 b=-1+根号2 或b=-1-根号2
(2)(X+Y+Z)^2=X2+Y2+Z2+2XY+2XZ+2YZ=9 那么X2+Y2+Z2=9-4=5
(3)Y2-X2=-(X-Y)(X+Y)那么原式等于-(x-y)6(x+y)8=-a3*b4
(4)(x-y)2=x2+y2-2xy=5-2xy=16 那么xy=-5.5 x3-y3=(x-y)(x2+y2+xy)
=4*-0.5=-2
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