已知x^2-y^2=24,x-y=-6,求代数式5x+5y的值.快,请高手指教啊```````
问题描述:
已知x^2-y^2=24,x-y=-6,求代数式5x+5y的值.快,请高手指教啊```````
答
(x-y)(x+y)=24 6(x+y)=24 x+y=-4 5x+5y=5(x+y)=-20
已知x^2-y^2=24,x-y=-6,求代数式5x+5y的值.快,请高手指教啊```````
(x-y)(x+y)=24 6(x+y)=24 x+y=-4 5x+5y=5(x+y)=-20