已知x、y的值满足等式(x+1)/2=(y+3)/4=(x+y)/5,求式子(3x+2y+1)/(x+2y+3)的值
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已知x、y的值满足等式(x+1)/2=(y+3)/4=(x+y)/5,求式子(3x+2y+1)/(x+2y+3)的值
已知x、y的值满足等式(x+1)/2=(y+3)/4=(x+y)/5,求式子(3x+2y+1)/(x+2y+3)的值
已知x、y的值满足等式(x+1)/2=(y+3)/4=(x+y)/5,求式子(3x+2y+1)/(x+2y+3)的值
设(x+1)/2=(y+3)/4=(x+y)/5=t
则x=2t-1,y=4t-3,x+y=5t
∴ 6t-4=5t
∴ t=4
∴ x=7,y=13
∴ (3x+2y+1)/(x+2y+3)
=(21+26+1)/(7+26+3)
=48/36
=4/3
(x+1)/2=(y+3)/4=(x+y)/5
∴(x+1)/2=(y+3)/4 (1)
(y+3)/4=(x+y)/5 (2)
由(1)得
2x+2=y+3
∴y=2x-1 (3)
由(2)得
5y+15=4x+4y
4x-y...
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(x+1)/2=(y+3)/4=(x+y)/5
∴(x+1)/2=(y+3)/4 (1)
(y+3)/4=(x+y)/5 (2)
由(1)得
2x+2=y+3
∴y=2x-1 (3)
由(2)得
5y+15=4x+4y
4x-y=15 (4)
把(3)代入(4)得
4x-2x+1=15
∴x=7
把x=7代入(3)得
y=13
∴(3x+2y+1)/(x+2y+3)
=(21+26+1)/(7+26+3)
=48/36
=4/3
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