解方程 3(2X-Y)+4(X-2Y)=87 2(3X-Y)-3(X-Y)=82 1-0.3(Y-2)=(X+1)/5 (Y-3)/4=(4X+9)/20-15 X+Y=

题目

解方程 3(2X-Y)+4(X-2Y)=87 2(3X-Y)-3(X-Y)=82 1-0.3(Y-2)=(X+1)/5 (Y-3)/4=(4X+9)/20-15 X+Y=
3(2X-Y)+4(X-2Y)=87
2(3X-Y)-3(X-Y)=82
1-0.3(Y-2)=(X+1)/5
(Y-3)/4=(4X+9)/20-15
X+Y= 2800
0.96X+0.64Y=2800*0.92

答案

(1)原式：3(2X-Y)+4(X-2Y)=87 2(3X-Y)-3(X-Y)=82=> 10x-11y=873x+y=82 (=> y=82-3x代入10x-11y=87)=> 解为：x=23,y=13(2)原式：1-0.3(Y-2)=(X+1)/5 (Y-3)/4=(4X+9)/20-15 => 2x+3y=144x-5y=-276=> 4x+6y=284x-5y=-27...