2个数学题、急、吐血跪求!
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2个数学题、急、吐血跪求!
1.已知x:y:z=1/2:2/3:3/4,求(1)x/x+y-z(2)x-y/y-z
2.若a:b=1:根2,a:c=2:根6,计算 根2a+b+根3c/根6a+根3b+c.
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1.已知x:y:z=1/2:2/3:3/4,求(1)x/x+y-z(2)x-y/y-z
2.若a:b=1:根2,a:c=2:根6,计算 根2a+b+根3c/根6a+根3b+c.
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1.
(x+y-z)/x=(1/2+2/3+3/4)/(1/2)
=23/12/(1/2)
=23/6
所以x/(x+y-z)=6/23
(x-y)/(y-z)
=(1/2-2/3)/(2/3-3/4)
=(2/6)/1/12
=4
2.
a:c=1:(1/2*根6)
所以a:b:c=1:根2:(1/2*根6)
2a+b+根3c/根6a+根3b+c
=(2+根2+3根2/2)/(根6+根6+1/2*根6)
=(4+5根2)/5根6
(x+y-z)/x=(1/2+2/3+3/4)/(1/2)
=23/12/(1/2)
=23/6
所以x/(x+y-z)=6/23
(x-y)/(y-z)
=(1/2-2/3)/(2/3-3/4)
=(2/6)/1/12
=4
2.
a:c=1:(1/2*根6)
所以a:b:c=1:根2:(1/2*根6)
2a+b+根3c/根6a+根3b+c
=(2+根2+3根2/2)/(根6+根6+1/2*根6)
=(4+5根2)/5根6