Tìm số tự nhiên x,biết
d) 125+(24-x)=17
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\(26⋮\left(x-1\right);38⋮\left(x-1\right)\Rightarrow x-1\inƯC\left(26,38\right)=\left\{\pm2;\pm1\right\}\Rightarrow x\in\left\{-1;0;2;3\right\}\)
Mà x là số tự nhiên \(\Rightarrow x\in\left\{0;2;3\right\}\)
d) 26 = 2 . 13
38 = 2 . 19
ƯCLN(26,38) = 2
ƯC(26,38) = Ư(2) = 1,2
Mà theo đề bài : 26 ⋮ (x-1) ; 38 ⋮ (x-1)
Nên : x = 2 hoặc 3
d) Ta có: \(32\%-0.25:x=-\dfrac{17}{5}\)
\(\Leftrightarrow0.25:x=\dfrac{8}{25}+\dfrac{17}{5}=\dfrac{93}{25}\)
hay \(x=\dfrac{25}{372}\)
Vậy: \(x=\dfrac{25}{372}\)
e) Ta có: \(\left(x+\dfrac{1}{5}\right)^2+\dfrac{17}{25}=\dfrac{26}{25}\)
\(\Leftrightarrow\left(x+\dfrac{1}{5}\right)^2=\dfrac{9}{25}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{5}=\dfrac{3}{5}\\x+\dfrac{1}{5}=-\dfrac{3}{5}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{5}\\x=-\dfrac{4}{5}\end{matrix}\right.\)
Vậy: \(x\in\left\{\dfrac{2}{5};-\dfrac{4}{5}\right\}\)
f) Ta có: \(-\dfrac{32}{27}-\left(3x-\dfrac{7}{9}\right)^3=-\dfrac{24}{27}\)
\(\Leftrightarrow\left(3x-\dfrac{7}{9}\right)^3=\dfrac{-8}{27}\)
\(\Leftrightarrow3x-\dfrac{7}{9}=-\dfrac{2}{3}\)
\(\Leftrightarrow3x=\dfrac{1}{9}\)
hay \(x=\dfrac{1}{27}\)
g) Ta có: \(60\%\cdot x+0.4x+x:3=2\)
\(\Leftrightarrow\dfrac{4}{3}x=2\)
hay \(x=\dfrac{3}{2}\)
Vậy: \(x=\dfrac{3}{2}\)
h) PT \(\Leftrightarrow\left|\dfrac{20}{9}-x\right|=\dfrac{2}{9}\) \(\Rightarrow\left[{}\begin{matrix}\dfrac{20}{9}-x=\dfrac{2}{9}\\x-\dfrac{20}{9}=\dfrac{2}{9}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{22}{9}\end{matrix}\right.\)
Vậy ...
i) PT \(\Leftrightarrow\dfrac{8}{5}+\dfrac{2}{5}x=\dfrac{16}{5}\) \(\Leftrightarrow\dfrac{2}{5}x=\dfrac{8}{5}\) \(\Leftrightarrow x=4\)
Vậy ...
a, (x + 30) – 75 = 125
=> x + 30 = 125 + 75 = 200
=> x = 200 – 30
=> x = 170
Vậy x = 170
b, x – 72 : 36 = 18
=> x – 2 = 18
=> x = 18 + 2 = 20
Vậy x = 20
c, x – 17 = 54
=> x = 54 +17
=> x = 71.
Vậy x = 71
d, 36 – (x – 2) = 12
=> x – 2 = 36 – 12
=> x = 24 + 2 = 26
Vậy x = 26
e, 9x – 7 = 837
=>9x = 837 + 7 = 844
=> x = 844 9
Vậy x = 844 9
f, (x – 15) – 107 = 0
=> x – 15 = 107
=> x = 107 +15
=> x = 122.
Vậy x = 122
g, 134 + (116 – x) = 145
=> 116 – x = 145 – 134
=> x = 116 – 11
=> x = 5.
Vậy x = 5
a. 2x - 3 = 125 : 25
2x - 3 = 5
2x = 5 + 3
2x = 8
x = 8 : 2 = 4
b. 472 : ( 24 + 5x ) + 8 = 16
( 24 + 5x ) + 8 = 472 : 16
( 24 + 5x ) + 8 = 29,5
24 + 5x = 29,5 - 8
24 + 5x = 21,5
5x = 21,5 - 24
5x = -2,5
x = -2,5 : 5 = -0,5
a.
(2x - 3).25 =125
2x - 3 =125 : 25
2x - 3 = 5
2x =5 + 3
2x = 8
x = 8 :2
x =4
b.
472 : (24 +5x) + 2 mủ 3 =16
472 :(24 + 5x) + 8 = 16
472 :(24 + 5x) = 16 - 8
472 :(24 + 5x) = 8
24 + 5x = 472 : 8
24 + 5x =59
5x = 59 - 24
5x = 35
x =35:5
x = 7
5x =
\(\Rightarrow24-x=17-125=-108\\ \Rightarrow x=24-\left(-108\right)=24+108=132\)
\(125+\left(24-x\right)=17\)
\(\Rightarrow24-x=17-125\)
\(\Rightarrow24-x=-108\)
\(\Rightarrow-x=-108-24\)
\(\Rightarrow-x=-132\)
\(\Rightarrow x=132\)