Question

若二元一次方程组3a-2b=11 4a+3b=9的解为a=3 b=-1，则由3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9，可得x+y=

x-y= ,从而求得x= ,y= .

Answer 1

3a-2b=11---- (1)
3(x+y)-2(x-y)=11------(2)
compare
a=(x+y)
b=(x-y)
a=3 所以 x+y=3

Answer 2

x+y=a=3

Answer 3

3a-2b=3（x+y)-2（x-y) 4a+3b=4（x+y)+3（x-y) x+y=a =3

追问

x-y= ,从而求得x= ,y=

追答

x-y=b=-1 即x+y=3 x-y=-1 x=1 y=2

Answer 4

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

Answer 5

x+y=a=3
X-y=b=-1

x=1 y=2