Question

解方程组2(x-1)-3(y+2)=1 3(x-1)+5(y+2)=12.9

Answer 1

2(x-1)-3(y+2)=1

2x-2-3y-6=1

2x-3y=1+2+6

2x-3y=9(1)

3(x-1)+5(y+2)=12.9

3x-3+5y+10=12.9

3x+5y=12.9+3-10

3x+5y=5.9(2)

(1)*5得：10x-15y=45(3)

(1)*3得：9x+15y=17.7(4)

(3)+(4)得：19x=62.7

x=3.3

将x=3.3带入（1）得：2*3.3-3y=9

y=-0.8

所以方程组的解为x=3.3,y=-0.8