若X+6Y+4Z=10 4X+4Y+Z=15求X+Y+Z
问题描述:
若X+6Y+4Z=10 4X+4Y+Z=15求X+Y+Z
答
X+6Y+4Z+4X+4Y+Z=25
5X+10Y+5Z=25
X+2Y+Z=5
Z=5-X-2Y Z=15-4X-4Y
5-X-2Y=15-4X-4Y 3X+2Y=10 X=(10-2Y)/3
X=5-2Y-Z X=10-6Y-4Z
5-2Y-Z=10-6Y-4Z 4Y+3Z=5 Z=(5-4Y)/3
(10-2Y)/3+6Y+4*(5-4Y)/3=10
10-2Y+18Y+20-16Y=30Y
Y=0.5
X+Y+Z=3+0.5+1=4.5