Question

1.已知a-b=1,a的二次方+b的二次方=25,求ab.？

Answer 1

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=-2,6,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...,1,1.（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=12,0,1.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.