解:方程(1)化简得:X2/X1=4/3 (1)'
方程(2)化简得:2X1+3X2=54 (2)'
由 (1)'得X2=4/3 X1 将其带入 (2)':
2X1+3*(4/3 X1)=54
2X1+4X1=54
X1=9
那么X2=4/3 X1 =12
3x2 ^2/6x1x2=20/30 (1)
x2 /2x1=2/3
x2=4/3x1
20x1+30x2=540 (2)
20x1+30 *4/3x1=540
20x1+40x1=540
60x=540
x1=9
x2=4/3*9=12