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
\(\left|x-1\right|+\left|x+5\right|=\left|x-1\right|+\left|-x-5\right|\)
\(\Rightarrow\left|x-1\right|+\left|x+5\right|\ge\left|x-1-x-5\right|\)
\(\Rightarrow\left|x-1\right|+\left|x+5\right|\ge\left|-6\right|=6\)
dấu "=" xảy ra khi \(\left(x-1\right).\left(x+5\right)\ge0\)
\(\Rightarrow-5\le x\le1\)
Vậy x={-5,-4,-3,-2,-1,0,1}
b) \(\hept{\begin{cases}\left(2x-y+3\right)^4\ge0\\\left|y+2\right|\ge0\end{cases}}\)
mà \(\left(2x-y+3\right)^4+\left|y+2\right|=0\)
dấu "=" xảy ra khi \(\hept{\begin{cases}\left(2x-y+3\right)^4=0\\\left|y+2\right|=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=-\frac{5}{2}\\y=-2\end{cases}}\)
vậy \(x=-\frac{5}{2},y=-2\)
∣x−1∣+∣x+5∣=∣x−1∣+∣−x−5∣
⇒∣�−1∣+∣�+5∣≥∣�−1−�−5∣⇒∣x−1∣+∣x+5∣≥∣x−1−x−5∣
⇒∣�−1∣+∣�+5∣≥∣−6∣=6⇒∣x−1∣+∣x+5∣≥∣−6∣=6
dấu "=" xảy ra khi (�−1).(�+5)≥0(x−1).(x+5)≥0
⇒−5≤�≤1⇒−5≤x≤1
Vậy x={-5,-4,-3,-2,-1,0,1}
b) \hept{(2�−�+3)4≥0∣�+2∣≥0\hept{(2x−y+3)4≥0∣y+2∣≥0
mà (2�−�+3)4+∣�+2∣=0(2x−y+3)4+∣y+2∣=0
dấu "=" xảy ra khi \hept{(2�−�+3)4=0∣�+2∣=0\hept{(2x−y+3)4=0∣y+2∣=0
⇒\hept{�=−52�=−2⇒\hept{x=−25y=−2
vậy �=−52,�=−2x=−25,y=−2