1.已知a-b=1,a的二次方+b的二次方=25,求ab.2.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy.3.已知x-1/x=2,求x²+1/x²的值.4.如果a²+b²-2a+4b+5=0,求a、b的值.
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![1.已知a-b=1,a的二次方+b的二次方=25,求ab.2.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy.3.已知x-1/x=2,求x²+1/x²的值.4.如果a²+b²-2a+4b+5=0,求a、b的值.](/uploads/image/z/1157933-29-3.jpg?t=1.%E5%B7%B2%E7%9F%A5a-b%3D1%2Ca%E7%9A%84%E4%BA%8C%E6%AC%A1%E6%96%B9%2Bb%E7%9A%84%E4%BA%8C%E6%AC%A1%E6%96%B9%3D25%2C%E6%B1%82ab.2.x%28x-1%29-%28x%26%23178%3B-y%29%3D-2%2C%E6%B1%82%28x%26%23178%3B%2By%26%23178%3B%29%2F2-xy.3.%E5%B7%B2%E7%9F%A5x-1%2Fx%3D2%2C%E6%B1%82x%26%23178%3B%2B1%2Fx%26%23178%3B%E7%9A%84%E5%80%BC.4.%E5%A6%82%E6%9E%9Ca%26%23178%3B%2Bb%26%23178%3B-2a%2B4b%2B5%3D0%2C%E6%B1%82a%E3%80%81b%E7%9A%84%E5%80%BC.)
1.已知a-b=1,a的二次方+b的二次方=25,求ab.2.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy.3.已知x-1/x=2,求x²+1/x²的值.4.如果a²+b²-2a+4b+5=0,求a、b的值.
1.已知a-b=1,a的二次方+b的二次方=25,求ab.
2.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy.
3.已知x-1/x=2,求x²+1/x²的值.
4.如果a²+b²-2a+4b+5=0,求a、b的值.
1.已知a-b=1,a的二次方+b的二次方=25,求ab.2.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy.3.已知x-1/x=2,求x²+1/x²的值.4.如果a²+b²-2a+4b+5=0,求a、b的值.
1.已知a-b=1,a的二次方+b的二次方=25,求ab.
a^2+b^2=25 (a-b)^2=a^2-2ab+b^2 1=25-2ab 2ab=24 ab=12
2.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy.
x2-x-x^2+y=-2 y-x=-2 (y-x)^2=y^2-2xy+x^2=4 x^2+y^2=4+2xy
(x²+y²)/2-xy=(4+2xy)/2-xy=2+xy-xy=2
3.已知x-1/x=2,求x²+1/x²的值.
x-1/x=2 (x-1/x)^2=4 x^2-2+1/x^2=4 x^2+1/x^2=6
4.如果a²+b²-2a+4b+5=0,求a、b的值.
a^2-2a+1+b^2+4b+4=0 (a-1)^2+(b+2)^2=0 a1 b=-2
a-b=1,a=b+1,a的二次方+b的二次方=25,﹙b+1﹚²+b²=25,b=3,∴a=4第2.3.4.题.x(x-1)-(x²-y)=-2,求(x²+y²)/2-xy。 x2-x-x^2+y=-2 y-x=-2 (y-x)^2=y^2-2xy+x^2=4 x^2+y^2=4+2xy (x²+y²)/2-x...
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a-b=1,a=b+1,a的二次方+b的二次方=25,﹙b+1﹚²+b²=25,b=3,∴a=4
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1.(a-b)的平方=a方+2ab+b方=1
因为a方+b方=25所以2ab=25-1=24,ab=12