已知(X+Y)²=169,(Y-1)的三次方=-0.125,求 根号下X-根号下8XY-三次根号下2Y-7X的值.十万火急!
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![已知(X+Y)²=169,(Y-1)的三次方=-0.125,求 根号下X-根号下8XY-三次根号下2Y-7X的值.十万火急!](/uploads/image/z/649131-51-1.jpg?t=%E5%B7%B2%E7%9F%A5%EF%BC%88X%2BY%EF%BC%89%26%23178%3B%3D169%2C%EF%BC%88Y-1%EF%BC%89%E7%9A%84%E4%B8%89%E6%AC%A1%E6%96%B9%3D-0.125%2C%E6%B1%82+%E6%A0%B9%E5%8F%B7%E4%B8%8BX-%E6%A0%B9%E5%8F%B7%E4%B8%8B8XY-%E4%B8%89%E6%AC%A1%E6%A0%B9%E5%8F%B7%E4%B8%8B2Y-7X%E7%9A%84%E5%80%BC.%E5%8D%81%E4%B8%87%E7%81%AB%E6%80%A5%21)
已知(X+Y)²=169,(Y-1)的三次方=-0.125,求 根号下X-根号下8XY-三次根号下2Y-7X的值.十万火急!
已知(X+Y)²=169,(Y-1)的三次方=-0.125,求 根号下X-根号下8XY-三次根号下2Y-7X的值.十万火急!
已知(X+Y)²=169,(Y-1)的三次方=-0.125,求 根号下X-根号下8XY-三次根号下2Y-7X的值.十万火急!
(X+Y)²=169,(Y-1)的三次方=-0.125,
所以
X+Y=13或-13
Y-1=-0.5
从而
Y=0.5
X=13-0.5=12.5
根号下X-根号下8XY-三次根号下2Y-7X
=√12.5-√8*0.5*12.5-3次根号下(2*0.5-7*12.5)
=5√2/2-5√2-2*0.5-7*12.5
5√2/2-5√2-2*0.5-7*12.5