X - X x 2 + X : 1/5 = 28
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20 tháng 12 2021 lúc 20:39
Tìm x, biết
(x-1)^2-(5+x)(x-5)=28
\(\left(x-1\right)^2-\left(5+x\right)\left(x-5\right)=28\)
\(\Leftrightarrow\left(x-1\right)^2+\left(5+x\right)\left(5-x\right)=28\)
\(\Leftrightarrow x^2-2x+1+25-x^2=28\)
<=> -2x - 2 = 0
<=> x = -1
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Tìm x: X - X x 2 + X : 1/5= 28
=>-x+0,2x=28
=>-0,8x=28
hay x=-35
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\(x-x\times2+x:\dfrac{1}{5}=28\)
\(4x=28\)
\(x=28:4\)
\(x=7\)
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tính nhanh
1. 2/3 + 4/9 + 1/5 + 2/15 +3/2 - 17/18
2. 13/28 x 5/12 - 5/28 x 1/12
3. 19/4 x 15/23 - 15/4 x 7/23 + 15/4 x 11/23
\(1,\frac{2}{3}+\frac{4}{9}+\frac{1}{5}+\frac{2}{15}+\frac{3}{2}-\frac{17}{18}\)
\(< =>\frac{4}{9}+\frac{3}{2}+\left(\frac{2}{3}+\frac{1}{5}+\frac{2}{15}\right)-\frac{17}{18}\)
\(< =>\frac{8}{18}+\frac{27}{18}+\left(\frac{10}{15}+\frac{3}{15}+\frac{2}{15}\right)-\frac{17}{18}\)
\(< =>\frac{35}{18}+1-\frac{17}{18}\)
\(< =>\frac{53}{18}-\frac{17}{18}\)
\(< =>2\)
\(2,\frac{13}{28}\cdot\frac{5}{12}-\frac{5}{28}\cdot\frac{1}{12}\)
\(< =>\left(\frac{13}{28}-\frac{5}{28}\right)\cdot\left(\frac{5}{12}-\frac{1}{12}\right)\)
\(< =>\frac{2}{7}\cdot\frac{1}{3}\)
\(< =>\frac{2}{21}\)
\(3,\frac{19}{4}\cdot\frac{15}{23}-\frac{15}{4}\cdot\frac{7}{23}+\frac{15}{4}\cdot\frac{11}{23}\)
\(< =>\frac{285}{92}-\frac{105}{92}+\frac{165}{92}\)
\(< =>\frac{15}{4}\)
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bạn viết dấu gạch ngang của phân số như thế nào đấy nguyen thi hien
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bài 2: tìm x biết
a) ( x + 1 ).( 3 - x ) > 0
b) ( 4x - 3 ).( 5 - x ) < 0
c) 3/( x - 4 ).( x - 7 ) + 6/( x - 7 ).( x - 13 ) + 15/( x - 13 ).( x - 28 ) - 1/( x - 28 ) = -5/2
ai làm nhanh mk tk cho 3 cái
a) Ta có : ( x + 1 ).( 3 - x ) > 0
Th1 : \(\hept{\begin{cases}x+1>0\\3-x>0\end{cases}\Rightarrow\hept{\begin{cases}x>-1\\x>3\end{cases}\Rightarrow}x>3}\)
Th2 : \(\hept{\begin{cases}x+1< 0\\3-x< 0\end{cases}\Rightarrow\hept{\begin{cases}x< -1\\x< 3\end{cases}\Rightarrow}x< -1}\)
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tìm x
x+1/199 + x+2/198 + x+3/197 + x+4/196 + x+5/195 = -5
1/21 +1/28 +1/36 +........+2/ x(x+1)=2/9
1 x 3 x 5 + 2 x6 x10 + 4 x 12 x 20
1 x 5 x 7 + 2 x 10 x 14 + 4 x 20 x 28
1 x 3 x 5 + 2 x 6 x 10 + 4 x 12 x 20
=15 + 120 + 960
= 135 + 960
=1095
1 x5 x 7 + 2 x 10 x 14 + 4 x 20 x 28
=35 + 280 + 2240
= 2555
k nha
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Tính hợp lý nếu có thể:
a) -52 x (-2)2 + (-3)3
b) (-19 - 46) : (-13) - (-52) x (-22)
c) (135 - 35) x (-47) + 53 x (-48 - 52)
d) [(-3)13 : 95 - 73] : (-52) - |-14|
e) -105 : (-15) - 21 - 9 x (-2)3
g) (-51) x (-29) - 131 x 51 + |-102|
h) (83 - 107 - 854) - (107 - 554) + 117
k) (-5)2 x 32 x 53 x (-17) x (-1)2n, n thuộc N
n) -28 x (-19) - (-64) x 28 x 17 x |-28|
m) 73 x (28 - 56) - 28 x (73 + 56)
Đọc tiếp
Tính hợp lý nếu có thể:
a) -52 x (-2)2 + (-3)3
b) (-19 - 46) : (-13) - (-52) x (-22)
c) (135 - 35) x (-47) + 53 x (-48 - 52)
d) [(-3)13 : 95 - 73] : (-52) - |-14|
e) -105 : (-15) - 21 - 9 x (-2)3
g) (-51) x (-29) - 131 x 51 + |-102|
h) (83 - 107 - 854) - (107 - 554) + 117
k) (-5)2 x 32 x 53 x (-17) x (-1)2n, n thuộc N
n) -28 x (-19) - (-64) x 28 x 17 x |-28|
m) 73 x (28 - 56) - 28 x (73 + 56)
a: \(=-25\cdot4-27=-100-27=-127\)
b: \(=-65:\left(-13\right)-25\cdot4=5-100=-95\)
c: \(=100\cdot\left(-47\right)+53\cdot\left(-100\right)=100\cdot\left(-100\right)=-10000\)
d: \(=\left[\left(-3\right)^{13}:3^{10}-73\right]:\left(-5\right)^2-14\)
\(=\left(-100\right):25-14=-4-14=-18\)
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Tính nhanh :
1/2 x 17/5 x 1/6 + 1/3 x 71/5 x 1/4 - 1/12 x 28/5
1/3 x + 1/2 = -4/3
-2/3 - 4/3 x = -1/2
5/2 - 2 (x-1) = -2/3
7/-2 x - 1/3 = -1/2
8/5 - 1/2 : x = 8/3
-5/4 x - 1/2 x = -7/3
ét ô ét
+) \(\dfrac{1}{3}x=-\dfrac{4}{3}-\dfrac{1}{2}=-\dfrac{11}{6}\)
\(x=-\dfrac{11}{6}:\dfrac{1}{3}=-\dfrac{11}{2}\)
+) \(\dfrac{4}{3}x=-\dfrac{2}{3}+\dfrac{1}{2}=-\dfrac{1}{6}\)
\(x=-\dfrac{1}{6}:\dfrac{4}{3}=-\dfrac{1}{8}\)
+) \(2\left(x-1\right)=\dfrac{5}{2}+\dfrac{2}{3}=\dfrac{19}{6}\)
\(x-1=\dfrac{19}{12}\)
\(x=\dfrac{31}{12}\)
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\(\dfrac{1}{3}x+\dfrac{1}{2}=-\dfrac{4}{3}\)
\(\dfrac{1}{3}x=\left(-\dfrac{4}{3}\right)-\dfrac{1}{2}\)
\(\dfrac{1}{3}x=-\dfrac{11}{6}\)
\(x=\left(-\dfrac{11}{6}\right):\dfrac{1}{3}\)
\(x=-\dfrac{11}{2}\)
\(-\dfrac{2}{3}-\dfrac{4}{3}x=-\dfrac{1}{2}\)
\(\dfrac{4}{3}x=\left(-\dfrac{2}{3}\right)-\dfrac{-1}{2}\)
\(\dfrac{4}{3}x=-\dfrac{1}{6}\)
\(x=\left(-\dfrac{1}{6}\right):\dfrac{4}{3}\)
\(x=-\dfrac{1}{8}\)
\(\dfrac{5}{2}-2\left(x-1\right)=-\dfrac{2}{3}\)
\(2\left(x-1\right)=\dfrac{5}{2}-\left(-\dfrac{2}{3}\right)\)
\(2\left(x-1\right)=\dfrac{19}{6}\)
\(\left(x-1\right)=\dfrac{19}{6}:2\)
\(x-1=\dfrac{19}{12}\)
\(x=\dfrac{19}{12}+1\)
\(x=\dfrac{31}{12}\)
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\(\dfrac{7}{-2}x-\dfrac{1}{3}=-\dfrac{1}{2}\)
\(\dfrac{-7}{2}x-\dfrac{1}{3}=-\dfrac{1}{2}\)
\(\dfrac{-7}{2}x=\left(-\dfrac{1}{2}\right)+\dfrac{1}{3}\)
\(\dfrac{-7}{2}x=-\dfrac{1}{6}\)
\(x=\left(-\dfrac{1}{6}\right):\left(-\dfrac{7}{2}\right)\)
\(x=\dfrac{1}{21}\)
\(\dfrac{8}{5}-\dfrac{1}{2}:x=\dfrac{8}{3}\)
\(\dfrac{1}{2}:x=\dfrac{8}{5}-\dfrac{8}{3}\)
\(\dfrac{1}{2}:x=-\dfrac{16}{15}\)
\(x=\dfrac{1}{2}:\left(-\dfrac{16}{15}\right)\)
\(x=-\dfrac{15}{32}\)
\(-\dfrac{5}{4}x-\dfrac{1}{2}x=-\dfrac{7}{3}\)
\(x\cdot\left(-\dfrac{5}{4}-\dfrac{1}{2}\right)=-\dfrac{7}{3}\)
\(x\cdot\left(-\dfrac{7}{4}\right)=-\dfrac{7}{3}\)
\(x=\left(-\dfrac{7}{3}\right):\left(-\dfrac{7}{4}\right)\)
\(x=\dfrac{4}{3}\)
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