Question

已知X＝M,Y＝N和X＝N,Y＝M是方程2X-3Y＝1的解,则代数式2M-6/3N-5的值为多少?

Answer 1

把X＝M,Y＝N和X＝N,Y＝M代入方程2X-3Y＝1中得到方程组

2M-3N=1

2N-3M=1

解得M=-1

N=-1

(2M-6)/(3N-5)

=(-1*2-6)/(-1*3-5)

=(-8)/(-8)

=1