高分悬赏 一道方程题

把X=3 Y=4
代入已知方程得
3A1+4B1=C1
3A2+4B2=C2

3A1B2X+B1B2Y=5C1B2
3A2B1X+B1B2Y=5C2B1
X=5(C1B2-C2B1)/[3(A1B2-A2B1)]
=5[(3A1+4B1)B2-(3A2+4B2)B1)/[3(A1B2-A2B1)]
=5[3A1B2+4B1B2-3A2B1-4B1B2)/[3(A1B2-A2B1)]
=5
3A1A2X+2A2B1Y=5C1A2
3A1A2X+2A1B2Y=5C2A1
Y=5(C1A2-C2A1)/(2A2B1-2A1B2)
=5[(3A1+4B1)A2-(3A2+4B2)A1)/(2A2B1-2A1B2)
=5(3A1A2+4B1A2-3A2A1-4B2A1)/(2A2B1-2A1B2)
=5*4/2=10
即X=5 Y=10