Question

已知方程组ax+by=4,cx+dy=5的解是x=4,y=3,求方程组3ax+2by=24,3cx+2dy=30的解,我

Answer 1

ax+by=4,cx+dy=5的解是x=4,y=3,

即4a+3b=4,4c+3d=5.(1)

3ax+2by=24,3cx+2dy=30,两边都除以6:

a/2*x+b/3*y=4,c/2*x+d/3*y=5

与(1)式对比得:

x/2=4,y/3=3

即方程组二的解是:x=8,y=9