已知a+b/3=2c-b/4=2a+c/5,求3a+2b+c/2a+b-c的值。
已知a+b/3=2c-b/4=2a+c/5,求3a+2b+c/2a+b-c的值。
解:设﹙a+b﹚/3=﹙2c-b﹚/4=﹙2a+c﹚/5=k
a+b=3k
2c-b=4k
2a+c=5k
解得: a=k
b=2k
c=3k
∴ ﹙3a+2b+c﹚/﹙2a+b-c﹚=﹙3k+4k+3k﹚/﹙2k+2k-3k﹚=10k/k=10.
10/7
解析:
(a+b)/3=(2c-b)/4=(2a+c)/5=k
则,
a+b=3k.........①
2c-b=4k........②
2a+c=5k.........③
①+②+③,得:
3a+3c=12k
a+c=4k
代入③,得:a=k
代入①,得:b=2k
代入②,得:c=3k
所以,
(3a+2b+c)/(2a+b-c)
=(3k+4k+3k)/(2k+2k+3k)
=10/7
已知3a-b/3=2a+c/5=2b+c/7,则a:b:c=
a:b:c=11:12:35
解法:令3a-b/3=2a+c/5=2b+c/7=k,然后用k表示出a,b,c。
已知a/2=b/3=c/5,求(3a+2b-2c)/(2a-b+c)的值。急!
解:设a/2=b/3=c/5=k
则a=2k.b=3k,c=5k
(3a+2b-2c)/(2a-b+c)
=(6k+6k-10k)/(4k-3k+5k)
=2k/6k
=1/3
已知a/2 = b/5 = c/3 求 代数式(2a+b-c)/(3a-b+c)的值
a/2 = b/5 = c/3 =k
a=2k
b=5k
c=3k
(2a+b-c)/(3a-b+c)=(4k+5k-3k)/(6k-5k+3k)=3/2
已知a:b:c=2:3:5,a+b+c=5求3a+2b-c/a+2b+c的值
a/b/c=2:3:5
a+b+c=5
求出a=2*5/(2+3+5)=1 b=1.5 c=2.5
3a+2b-c/a+2b+c=3.5/6.5=7/13
初中方程题,已知,3a-b/3=2a+c/5=2b+c/7,求2a-b+c/a+b+2c,急!
设
3a-b/3=2a+c/5=2b+c/7=k
则
3a-b=3k........(1)
2a+c=5k......(2)
2b+c=7k......(3)
(3)-(2)得
2b-2a=2k
b-a=k........(4)
(1)+(4)得
2a=4k
a=2k
代入(4)得
b-2k=k
b=3k
代入(3)得
6k+c=7k
c=k
解得
a=2k
b=3k
c=k
则
2a-b+c/a+b+2c
=(4k-3k+k)/(2k+3k+2k)
=2k/7k
=2/7
已知a/2=b/3=c/5,求3a+2b-2c/2a-b+c的值 。谢谢
设a/2=b/3=c/5=t,a=2t,b=3t,c=5t;(3a+2b-2c)/(2a-b+c)=(6t+6t-10t)/(4t-3t+5t)=2t/6t=1/3
已知a=2b,c=3a,求a+3b-2c/4a+2b+c的值
a=2b
所以c=3a=6b
所以原式=(2b+3b-12b)/(8b+2b+6b)
=-7b/16b
=-7/16
3a-b/3=2a+c/5=2b+c/7,则a:b:c=( )
设3a-b=3k
2a+c=5K
2b+c=7K a=2k, b=3k, c=k a:b:c=2:3:1