tim x dua vao quan he uoc boi:tim so tu nhien x sao cho x-1 la uoc cua 12tim so tu nhien x sao cho 2x+1 la uoc cua 28tim so tu nhien x sao cho x+15 la boi cua x+3tim cac so nguyen x,y sao cho (x+1)(y-2)=3tim so nguyen x sao cho(x+2).(y-1)=2tim so nguyen to x vua la uoc cua 275 vua la uoc cua 180tim so nguyen to x,y biet x+y=12 va UCLL (x:y)=5tim so tu nhien x,y biet x+y=32 va UCLL (x:y)=8tim so tu nhien x biet x chia het cho10; xchia het cho12; x chia het cho15 va 100<x<150tim so x nho nhat khac 0b...
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tim x dua vao quan he uoc boi:
tim so tu nhien x sao cho x-1 la uoc cua 12
tim so tu nhien x sao cho 2x+1 la uoc cua 28
tim so tu nhien x sao cho x+15 la boi cua x+3
tim cac so nguyen x,y sao cho (x+1)(y-2)=3
tim so nguyen x sao cho(x+2).(y-1)=2
tim so nguyen to x vua la uoc cua 275 vua la uoc cua 180
tim so nguyen to x,y biet x+y=12 va UCLL (x:y)=5
tim so tu nhien x,y biet x+y=32 va UCLL (x:y)=8
tim so tu nhien x biet x chia het cho10; xchia het cho12; x chia het cho15 va 100<x<150
tim so x nho nhat khac 0b biet x chia het cho 24 va 30
40 chia het cho x . 56 chia het cho x va x>6
Áp dụng tính chất của dãy tỉ số bằng nhau, ta có :
\(\frac{2x+1}{5}=\frac{4y-2}{7}=\frac{2x+4y-1}{6x}=\frac{\left(2x+1\right)+\left(4y-2\right)}{5+7}=\frac{2x+4y-1}{12}\)
\(\Rightarrow\frac{2x+4y-1}{6x}=\frac{2x+4y-1}{12}\)
\(\Rightarrow6x=12\)
\(\Rightarrow x=2\)
Thay x = 2 , ta được :
\(\frac{2x+1}{5}=\frac{4y-2}{7}\)
hay \(1=\frac{4y-2}{7}\Rightarrow4y-2=7\Rightarrow4y=9\Rightarrow y=\frac{9}{4}\)
Vậy x = 2 ; y = \(\frac{9}{4}\)