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1)-2x-(-17)=15
=>-2x=15-17
=>-2x=-2
=>x=1
Vậy x=1
2)|x|-10=-3
=>|x|=7
=>\(x=\left[{}\begin{matrix}7\\-7\end{matrix}\right.\)
Vậy x=7 hoặc x=-7
3)(x+2).(x-9)=0
\(\Rightarrow\left[{}\begin{matrix}x+2=0\\x-9=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-2\\x=9\end{matrix}\right.\)
Vậy x=-2 hoặc x=9
Ta có
\(x⋮12,x⋮10\)
Nên \(x\in BC\left(12;10\right)=2^2.3.5=60\)
\(x=60k\left(k\inℤ\right)\)
Mà \(-200\le x\le200\)
Nên \(60.\left(-3\right)\le60k\le60.3\)
Nên \(k\le\left|3\right|\)
Vậy \(x\in\left\{60.\left(-3\right);60.\left(-2\right);60.\left(-1\right);0;60.1;60.2;60.3\right\}\)
Do đó \(x\in\left\{-180;-120;-60;0;60;120;180\right\}\)
\(\)
\(x⋮12,x⋮10\)
\(\Rightarrow x\in B\left(12,10\right)\)
\(12=2^2.3\)
\(10=2.5\)
\(\Rightarrow BCNN\left(12,10\right)=2^2.3.5=60\)
\(\Rightarrow BC\left(12,10\right)=B\left(60\right)=\left\{0;\pm60;\pm120;\pm180;\pm240;...\right\}\)
Mà \(-200\le x\le200\)
\(\Rightarrow x\in\left\{0;\pm60;\pm120;\pm180\right\}\)
PP/ss: Hoq chắc ạ :'(
a, x \(⋮12\Rightarrow x\in B\left(12\right)=\left\{0;\pm12;\pm24;...\right\}\)
b, x \(⋮10\Rightarrow x\in B\left(10\right)\) và -200 \(\le x\le200\Rightarrow x=\left\{0;\pm10;\pm20;...;\pm200\right\}\)
@Nguyễn Hải Linh
\(A=\left\{36;48;60;72\right\}\)
\(B=\left\{0;15;30;45;60;75;90\right\}\)
\(C=\left\{12;18\right\}\)
\(D=\left\{1;3;9\right\}\)
A={36;48;60;72}
B={0;15;30;45;60;75;90}
C= {18;12}
D={1;3;9}
hok tốt nha!!
a)U(20)={1,2,4,5,10,20}
do x\(\in\)U(20) và 0<x<10 nen x={1,2,4,5}
b)U(30)={1,2,3,5,6,10,15,30}
do x\(\in\)U(30) và 5<x\(\le\)20 nên x\(\in\){6,10,15}
c)B(4)={4,8,12,16,20,24,28,32,36,40,44,48,52,56,... }
do x\(\in\)B(4) và 16\(\le\)x\(\le\)50 nên x\(\in\){16,20,24,28,32,36,40,44,48 }
a) 80 \(⋮\)x
=> x \(\inƯ\left(80\right)=\left\{1;2;4;5;8;10;16;20;40;80\right\}\)
Mà x > 20 nên \(x\notin\left\{1;2;4;5;8;10;16;20\right\}\)
Vậy \(x\in\left\{40;80\right\}\)
b) \(x\inƯ\left(100\right)=\left\{1;2;5;10;20;25;50;100\right\}\)
Mà 5 < x < 20 => \(x\notin\left\{1;2;5;20;25;50;100\right\}\)
Vậy x = 10
c) \(x⋮17\)=> x \(\in\)B(17) = { \(0;17;34;51;...\)}
Mà 10 < x < 30 => \(x\notin\left\{0;34;51;...\right\}\)
=> x = 17
d) \(x\inƯ\left(45\right)\)
=> \(x\in\left\{1;3;5;9;15;45\right\}\)
Mà x > 5 => x \(\notin\left\{1;3;5\right\}\)
Vậy \(x\in\left\{9;15;45\right\}\)
e) \(x\in B\left(15\right)=\left\{0;15;30;45;60;75;90;...;195;210...\right\}\)
Mà \(100\le x\le200\)=> \(x\notin\left\{0;15;30;...;90\right\}\)
Vậy \(x\in\left\{105;120;135;150;165;180;195\right\}\)
Còn câu j tự làm
x ⋮ 12; x ⋮ 10\(\Rightarrow\)x\(\in\)BC(12,10)
\(\Rightarrow x\in B\left(60\right)\) mà -200 ≤ x ≤ 200
=> x\(\in\){-180,-120,-60,0,60,120,180}