已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² 已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² + xY- 2Y² =求x² - 4x Y+ Y² =
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![已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² 已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² + xY- 2Y² =求x² - 4x Y+ Y² =](/uploads/image/z/12967331-59-1.jpg?t=%E5%B7%B2%E7%9F%A5x%26sup2%3B+-XY+%3D+2%2CY%26sup2%3B+-XY%3D+5%2C%E6%B1%82x%26sup2%3B+-+4x+Y%2B+Y%26sup2%3B+%3D+2x%26sup2%3B+%2B+xY+-3Y%26sup2%3B+%3D+x%26sup2%3B+%E5%B7%B2%E7%9F%A5x%26sup2%3B+-XY+%3D+2%2CY%26sup2%3B+-XY%3D+5%2C%E6%B1%82x%26sup2%3B+-+4x+Y%2B+Y%26sup2%3B+%3D+2x%26sup2%3B+%2B+xY+-3Y%26sup2%3B+%3D+x%26sup2%3B+%2B+xY-+2Y%26sup2%3B+%3D%E6%B1%82x%26sup2%3B+-+4x+Y%2B+Y%26sup2%3B+%3D)
已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² 已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² + xY- 2Y² =求x² - 4x Y+ Y² =
已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x²
已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² + xY- 2Y² =
求x² - 4x Y+ Y² =
已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² 已知x² -XY = 2,Y² -XY= 5,求x² - 4x Y+ Y² = 2x² + xY -3Y² = x² + xY- 2Y² =求x² - 4x Y+ Y² =
2x^2+xy-3y^2
=2x^2-2xy+3xy-3y^2
=2(x^2-xy)-3(y^2-xy)
=2×2-3×5
=-11
x^2+xy-2y^2
=x^2-xy+2xy-2y^2
=(x^2-xy)-2(y^2-xy)
=2-2×5
=-8