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\(\frac{x+10}{90}+\frac{x+20}{80}+\frac{x+30}{70}+\frac{x+40}{60}+\frac{x+50}{50}=-5\)
<=> \(\frac{x+10}{90}+1+\frac{x+20}{80}+1+\frac{x+30}{70}+1+\frac{x+40}{60}+1+\frac{x+50}{50}+1=0\)
<=> \(\frac{x+100}{90}+\frac{x+100}{80}+\frac{x+100}{70}+\frac{x+100}{60}+\frac{x+100}{50}=0\)
<=> \(\left(x+100\right)\left(\frac{1}{90}+\frac{1}{80}+\frac{1}{70}+\frac{1}{60}+\frac{1}{50}\right)=0\)
<=> x + 100 = 0
<=> x = -100
Vậy x = -100
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 }
\(\Rightarrow\frac{x+10}{490}+\frac{x+20}{480}+\frac{x+30}{470}+\frac{x+40}{460}+\frac{x+50}{450}+5=0\)
\(\Rightarrow\frac{x+10}{490}+1+\frac{x+20}{480}+1+\frac{x+30}{470}+1+\frac{x+40}{460}+1+\frac{x+50}{450}+1=0\)
\(\Rightarrow\frac{x+500}{490}+\frac{x+500}{480}+\frac{x+500}{470}+\frac{x+500}{460}+\frac{x+500}{450}=0\)
\(\Rightarrow\left(x+500\right).\left(\frac{1}{490}+\frac{1}{480}+\frac{1}{470}+\frac{1}{460}+\frac{1}{450}\right)=0\Rightarrow x+500=0\Rightarrow x=-500\)
a: x/5=32/80
nên x/5=2/5
hay x=2
13/x=26/30
nên 13/x=13/15
hay x=15
-x/7=22/-77
=>x/7=2/7
hay x=2
b: x/9=28/36
=>x/9=7/9
hay x=7
-10/x=50/55
=>-10/x=10/11
hay x=-11
a) A = {x E Ư(12); x < 6}
A = { 1;2;3;4}
b) B = { 24;36;48}
c) C = {15;30}
d) D = {15;20;25;30;25;40;45;50;55;.......;90;95}
\(x⋮12;25;30\Rightarrow x\in BC\left(12;25;30\right)\)
\(12=2^2.3;25=5^2;30=2.3.5\)
\(BCNN\left(12;25;30\right)=2^2.3.5^2=300\)
\(BC\left(12;25;30\right)=B\left(300\right)\)
\(B\left(300\right)=\left\{0;300;600;....\right\}\)
\(0\le x\le500\Rightarrow x=300\)
\(\left(3x-2^4\right).7^3=2.7^4\)
\(\left(3x-16\right)=2.7\)
\(3x-16=14\)
\(3x=30\)
\(x=10\)
\(\left|x-5\right|=16+2.\left(-3\right)\)
\(\left|x-5\right|=10\)
\(\Leftrightarrow x-5=10\Rightarrow x=15\)
\(\Leftrightarrow x-5=-10\Rightarrow x=-5\)
a, B(15)=\(\left\{0,15,30,45,60,75,90,...\right\}\)
Vì 40\(\le\)x\(\le\)70 => x=\(\left\{45,60\right\}\)
b,x \(⋮\)12 và 0 < x < 30
=> x\(\in\)Ư( 12) =\(\left\{1,2,3,4,6,12\right\}\)
Vì 0 < x < 30 => x=\(\left\{1,2,3,4,6,12\right\}\)
c, x\(⋮\)8 và 2 \(\le\) x \(\le\)20
=> x \(\in\)Ư(8) = \(\left\{1,2,4,8\right\}\)
Vì 2 \(\le\)x \(\le\)20 => x= \(\left\{2,4,8\right\}\)
d, x\(\in\) Ư(30) và x > 1^2
Mà Ư(30)=\(\left\{1,2,3,5,6,10,15,30\right\}\)
Vì x> 1^2 => x=\(\left\{2,3,5,6,10,15,30\right\}\)
e, 8\(⋮\) x
=> x\(\in\) B(8)
Chúc bạn học tốt , tick cho mk nhé
\(\left(x+50\%\right):\frac{7}{8}=\frac{5}{7}\)
\(\Rightarrow\left(x+\frac{1}{2}\right)=\frac{5}{7}.\frac{7}{8}\)
\(\Rightarrow x+\frac{1}{2}=\frac{5}{8}\)
\(\Rightarrow x=\frac{5}{8}-\frac{1}{2}\)
\(\Rightarrow x=\frac{1}{8}\)
Vậy...
Mình làm tiếp bài của bạn " I have a crazy idea "
b) \(\frac{25-x}{3}=\frac{15}{2}\)
Áp dụng tỉ lệ thức:
\(\left(25-x\right).2=15.3\)
\(\Rightarrow25-x=\frac{15.3}{2}=\frac{45}{2}\Leftrightarrow x=25-\frac{45}{2}=\frac{5}{2}\)
c) \(x-\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-\frac{1}{20}-\frac{1}{30}-\frac{1}{42}=1\)
\(\Rightarrow x-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\right)=1\)
\(\Rightarrow x-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\right)=1\)
\(\Rightarrow x-\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{6}-\frac{1}{7}\right)=1\)
\(\Rightarrow x-\left(\frac{1}{1}-\frac{1}{7}\right)=1\Leftrightarrow x-\frac{6}{7}=1\Leftrightarrow x=1+\frac{6}{7}=\frac{13}{7}\)
1/2(x-1)=50
x-1=100
x=101
2/5(x-1)=4,4
x-1=4
x=5