解方程组:{x²-2xy+3y²=9 4x²-5xy+6y²=30
问题描述:
解方程组:{x²-2xy+3y²=9 4x²-5xy+6y²=30
答
x2-2xy+3y2=9得:x2=9-(-2xy+3y2)带入4x2-5xy+6y2=30得:4*(9-(-2xy+3y2)-5xy+6y2=30得:2y2-xy-2=0带入x2-2xy+3y2=9得x2=y2+5由2y2-xy-2=0得2y2-xy-2=0即x=2(y-1/y)带入x2=y2+5得4*(y2-2+1/y2)=y2+5得3*y2-1...