Question

代入法解下列方程组：3m-4n=79m-10n+23=0

Answer 1

(1)3m-4n=7 → 4n=7-3m →n=(7-3m)/4

(2)9m-10n+23=0

代入(2)得 9m-10(7-3m)/4=-23

36m-70+30m=-92

66m =-22

m=-1/3

代入(1)得 3×(-1/3)-4n=7

-1-4n=7

-4n=8

n=-2

所以m=-1/3,n=-2