a + b + c + d = 8
a + 2c = 3b
b + 2d = 3c
c + 2a = 3d
d + 2b = 3a
由上4个式子可知,a,b,c,d任意交换位置等式仍然成立,既有a = b = c = d
又由于a + b + c + d = 8
故 a = b = c = d = 2
即有：
a + 2b = 6
3c + 4d = 14
a+b+c+d=8,且a+2c=3b,b+2d=3c,c+2a=3d,d+2b=3a,求a+2b
1个回答
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