方程组2x+3y=1kx+(k−1)y=2x与y的值相等,则k的值为( ) A.15 B.92 C.112 D.5
问题描述:
方程组
x与y的值相等,则k的值为( )
2x+3y=1 kx+(k−1)y=2
A.
1 5
B.
9 2
C.
11 2
D. 5
答
已知方程组,2x+3y=1…①kx+(k−1)y=2••②,将①×k2-②得,32ky-(k-1)y=0.5k-2,解得,y=0.5k−20.5k+1,把y代入方程①,解得x=−k+7k+2(k≠-2),∵方程组2x+3y=1kx+(k−1)y=2x与y的值相等,∴0.5k−20.5...