若方程组{2X+3Y=K+4 X-Y=3K-3的解满足X+Y=5,求K的值

问题描述:

若方程组{2X+3Y=K+4 X-Y=3K-3的解满足X+Y=5,求K的值

2X+3Y=K+4 (1)
X-Y=3K-3 (2)
(1)*2+(2)
4X+6Y+X-Y=2K+8+3K-3
5X+5Y=5K+5
X+Y=K+1=5
K=4