三元一次方程组x+y+t=51 4x+8y+5t=300 4.5x+9y+7.5t=360

显示全部楼层 · 2013-4-12 15:21:48

x+y+t=51......① 4x+8y+5t=300......② 4.5x+9y+7.5t=360......③由③×2-②×2-①得，9x+18y+15t-8x-16y-10t-x-y-z=360×2-300×2-51

y+4t=69......④由②-①×4得, 4x+8y+5t-4x-4y-4z=300-51×4
4y+t=96......⑤由④×4-⑤得，4y+16t-4y+t=69×4-...

千问 · 2013-4-12 15:21:48

x+y+t=51 ①4x+8y+5t=300 ②→x+2y= ④ 4.5x+9y+7.5t=360③→x+2y= ⑤④-⑤→t=?将其代入①、④→x+y=?x+2y=?解得x=18，y=21，t=12...

千问 · 2013-4-12 15:21:48

x+y+t=51 ①4x+8y+5t=300 ②→x+2y= ④ 4.5x+9y+7.5t=360③→x+2y= ⑤④-⑤→t=?将其代入①、④→x+y=?x+2y=?解得X=?y=?...

千问 · 2013-4-12 15:21:48

X=18，Y=21，T=12...