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a. 2x + 70 = 74
<=> 2x = 4
<=> x = 2
b. 120 - \(\dfrac{4x}{2}\) = 80
<=> 120 - 2x = 80
<=> 120 - 80 = 2x
<=> 2x = 40
<=> x = 20
c. (3x + 5)2 = 400
<=> \(|3x+5|=\sqrt{400}\)
<=> \(|3x+5|=20\)
<=> \(\left[{}\begin{matrix}3x+5=20\\3x+5=-20\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{-25}{3}\end{matrix}\right.\)
a. 2x+\(\dfrac{4}{5}\)=0 hoặc 3x-\(\dfrac{1}{2}\)=0
2x=- 4/5 hoặc 3x=1/2
x=-2/5 hoặc x=\(\dfrac{1}{6}\)
b. x-\(\dfrac{2}{5}\)=0 hoặc x+\(\dfrac{4}{7}\)=0
x=2/5 hoặc x=-\(\dfrac{4}{7}\)
d. x(1+5/8-12/16)=1
\(\dfrac{7}{8}\)x=1=> x=8/7
\(156-\left(x+61\right)=82\)
\(\left(x+61\right)=156-82\)
\(\left(x+61\right)=74\)
\(\Rightarrow x=13\)
PP/ss: Lm từng câu ạ ((:
\(156-\left(x+61\right)=82\)
\(\Rightarrow x+61=156-82\)
\(\Rightarrow x+61=74\)
\(\Rightarrow x=74-61\)
\(\Rightarrow x=13\)
b) /2x-5/=13
=>2x-5=13 hoặc -13
TH1: 2x-5=13 | TH2:2x-5=-13 |
2x=13+5=>2x=18 | 2x=-13+5=>2x=-8 |
x=18:2=>x=9 | x=-8:2=>x=4 |
\(\left[\left(16x-30\right)\cdot8+80\right]:5=224\\ \Rightarrow2\left(8x-15\right)\cdot8+80=1120\\ \Rightarrow16\left(8x-15\right)=1040\\ \Rightarrow8x+15=65\Rightarrow x=\dfrac{65-15}{8}=\dfrac{25}{4}=6,25\)
\(\dfrac{\left[\left(16x-30\right).8\right]+80}{5}=224\)
<=> \(\dfrac{\left(128x-240\right)+80}{5}=224\)
<=> \(\dfrac{128x-240+80}{5}=224\)
<=> \(\dfrac{128x-160}{5}=224\)
<=> 128x - 160 = 224 . 5
<=> 128x - 160 = 1120
<=> 128x = 1120 +160
<=> 128x = 1280
<=> x = 10