(x-5)x30/100=200x/100+5
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(x-5) x \(\frac{30}{100}\)= 200x : 100 + 5
(x-5) x \(\frac{3}{10}\)= 200x : 100 + 5
\(\frac{x.3-15}{10}\)= 2x + 5
\(\frac{x.3-15}{10}-2x=5\)
\(\frac{x.3-15}{10}-\frac{20x}{10}=5\)
\(\frac{3x-15-20x}{10}=5\)
3x - 20x - 15 = 50
-17x - 15 = 50
-17x = 65
x = 65 : -17
x = \(\frac{-65}{17}\)
=>3/10(x-5)=2x+5
=>3/10x-3/2=2x+5
=>-17/10x=5+3/2=6/2+3/2=11/2
=>x=-55/17
a) \(2^{x+2}-2^2=96\)
<=> \(2^x.2^2-2^x=96\)
<=> \(2^x\left(4-1\right)=96\)
<=> \(3.2^x=96\)
<=> \(2^x=32\)
<=> \(2^x=2^5\)
<=> x = 5
b, \(x-\left(\frac{50x}{100}+\frac{25x}{200}\right)=11\frac{1}{4}\)
\(\Rightarrow x-\left(\frac{1x}{2}+\frac{1x}{8}\right)=\frac{45}{4}\)
\(\Rightarrow x-\left(\frac{4x}{8}+\frac{1x}{8}\right)=\frac{45}{4}\)
\(\Rightarrow x-\frac{5x}{8}=\frac{45}{4}\)
\(\Rightarrow\frac{8x}{8}-\frac{5x}{8}=\frac{45}{4}\)
\(\Rightarrow\frac{3x}{8}=\frac{45}{4}\Rightarrow x=\frac{45}{4}\div\frac{3}{8}=30\)
Vậy x = 30
a) pt a <=> 3x+1=0 hoặc x-2000=0 hoặc 3x+6000=0
<=> x=-1/3 hoặc x=2000 hoặc x=-2000
a, \(\left(x-5\right).30\%=\dfrac{20x}{100}+5\Rightarrow\left(x-5\right).\dfrac{3}{10}=\dfrac{x}{5}+5\)
\(\Rightarrow\dfrac{3}{10}x+\dfrac{3}{2}=\dfrac{x}{5}+5\Rightarrow\dfrac{3}{10}x-\dfrac{x}{5}=5-\dfrac{3}{2}\)
\(\Rightarrow x\left(\dfrac{3}{10}-\dfrac{1}{5}\right)=\dfrac{7}{2}\Rightarrow\dfrac{1}{10}x=\dfrac{7}{2}\Rightarrow x=35\)
b, \(\dfrac{x+3}{x-2}\in Z\)
Ta có: \(\dfrac{x-2+5}{x-2}=\dfrac{x-2}{x-2}+\dfrac{5}{x-2}=1+\dfrac{5}{x-2}\)
Để \(\dfrac{x+3}{x-2}\in Z\Leftrightarrow\dfrac{5}{x-2}\Leftrightarrow5⋮\left(x-2\right)\Rightarrow\left(x-2\right)\in U\left(5\right)\)
\(\Rightarrow\left(x-2\right)\in\left\{1;5\right\}\Rightarrow x\in\left\{-1;3\right\}\)
Kiến thức lâu k học :> sai gì bỏ qua giùm :<<