解三元一次方程组{2x+5y-3z=3(5x-4y)/3=72y+3z/2=7
( 5x - 4y )/3 = 7,5x - 4y = 21,5x = 21 + 4y,2x = 2( 21 + 4y )/5;
( 2y + 3z )/2 = 7,2y + 3z = 14,3z = 14 - 2y;
将 2x、3z 带入第一个方程,2( 21 + 4y )/5 + 5y - ( 14 - 2y ) = 3
2( 21 + 4y ) + 25y - 5( 14 - 2y ) = 15
43y = 43,y = 1;
2x = 2( 21 + 4y )/5 = 10,x = 2;
3z = 14 - 2y = 12,z = 4 。
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