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10 tháng 3 2017

5 + 5 : 5 x 15

= ( 5 + 5 ) : 5 x 15

=   10 : 5 x 15

= 2 x 15

= 30

5 + 5 : 5 x 15

= 5 + 1 x 15

= 5 + 15

= 20

27 tháng 7 2023

1) \(2^3\times x-5^2\times x=2\times\left(5^2+2^2\right)-33\)

\(x\times\left(2^3-5^2\right)=2\times\left(25+4\right)-33\)

\(x\times\left(8-25\right)=2\times29-33\)

\(x\times-17=25\)

\(x=-\dfrac{25}{17}\)

2) \(15\div\left(x+2\right)=\left(3^3+3\right)\div1\)

\(15\div\left(x+2\right)=\left(27+3\right)\div1\)

\(15\div\left(x+2\right)=30\div1\)

\(15\div\left(x+2\right)=30\)

\(x+2=\dfrac{1}{2}\)

\(x=-\dfrac{3}{2}\)

3) \(20\div\left(x+1\right)=\left(5^2+1\right)\div13\)

\(20\div\left(x+1\right)=\left(25+1\right)\div13\)

\(20\div\left(x+1\right)=26\div13\)

\(20\div\left(x+1\right)=2\)

\(x+1=20\div2\)

\(x+1=10\)

\(x=9\)

27 tháng 7 2023

4) \(320\div\left(x-1\right)=\left(5^3-5^2\right)\div4+15\)

\(320\div\left(x-1\right)=\left(125-25\right)\div4+15\)

\(320\div\left(x-1\right)=100\div4+15\)

\(320\div\left(x-1\right)=25+15\)

\(320\div\left(x-1\right)=40\)

\(x-1=8\)

\(x=9\)

5) \(240\div\left(x-5\right)=2^2\times5^2-20\)

\(240\div\left(x-5\right)=4\times25-20\)

\(240\div\left(x-5\right)=100-20\)

\(240\div\left(x-5\right)=80\)

\(x-5=30\)

\(x=35\)

6) \(70\div\left(x-3\right)=\left(3^4-1\right)\div4-10\)

\(70\div\left(x-3\right)=\left(81-1\right)\div4-10\)

\(70\div\left(x-3\right)=80\div4-10\)

\(70\div\left(x-3\right)=20-10\)

\(70\div\left(x-3\right)=10\)

\(x-3=7\)

\(x=10\)

a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)

\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)

=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)

b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)

\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)

Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)

c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)

\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)

=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)

d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)

\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6

=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)

24 tháng 3 2023

 a,  \(\dfrac{5\times11\times15\times18}{6\times15\times22\times10}\)

\(\dfrac{5\times11\times15\times6\times3}{6\times15\times11\times2\times2\times5}\)

\(\dfrac{5\times11\times15\times6}{5\times11\times15\times6}\) \(\times\) \(\dfrac{3}{2\times2}\)

= 1 \(\times\) \(\dfrac{3}{4}\)

\(\dfrac{3}{4}\)

b, \(\dfrac{7}{12}\) \(\times\) \(\dfrac{3}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(\dfrac{5}{12}\)

\(\dfrac{3}{5}\) \(\times\) ( \(\dfrac{7}{12}+\dfrac{5}{12}\))

\(\dfrac{3}{5}\) \(\times\) \(\dfrac{12}{12}\)

\(\dfrac{3}{5}\) \(\times\) 1 

\(\dfrac{3}{5}\)

15 tháng 1 2019

\(\left|x\right|=\left|-5\right|-\left|-10\right|+15\)

\(\Rightarrow\left|x\right|=5-10+15\)

\(\Rightarrow\left|x\right|=10\)

\(\Rightarrow x=\pm10\)

\(\left|x\right|=-(-12)+(-15)+8\)

\(\Rightarrow\left|x\right|=+12+(-15)+8\)

\(\Rightarrow\left|x\right|=12+(-15)+8\)

\(\Rightarrow\left|x\right|=(-3)+8\)

\(\Rightarrow\left|x\right|=5\)

\(\Rightarrow x=\pm5\)

Bài dưới tương tự

15 tháng 1 2019

|x|=|−5|−|−10|+15

⇒|x|=5−10+15

⇒|x|=10

⇒x=±10

|x|=−(−12)+(−15)+8

⇒|x|=+12+(−15)+8

⇒|x|=12+(−15)+8

⇒|x|=(−3)+8

⇒|x|=5

⇒x=±5

8 tháng 4 2017

1) -5 . x - ( - 3 )  = 13

-5 . x + 3 = 13

-5 . x = 13 - 3

-5 . x =10

x= 10 :  ( -5 )

x = -2

2) 3 . x  + 17 = 2

3 . x = 2 - 17

3 . x = -15

x = -15 : 3

x =  -5

3) (-5) . x =15

x = -3

4) 2x - (-17) = 15

2x + 17 = 15

2x = -2

x = -2 : 2

x= -1

5) -12 . ( x - 5 ) + 7 .(3-x) = 5

25 tháng 2 2018

1=10

2=-5

3=-1

4=5

29 tháng 12 2023

\(\left(x-5\right)^5=\left(x-5\right)^{15}\)

\(\left(x-5\right)^{15}-\left(x-5\right)^5=0\)

\(\left(x-5\right)^5\left[\left(x-5\right)^{10}-1\right]=0\)

\(\left(x-5\right)^5=0\) hoặc \(\left(x-5\right)^{10}-1=0\)

*) \(\left(x-5\right)^5=0\)

\(x-5=0\)

\(x=5\)

*) \(\left(x-5\right)^{10}-1=0\)

\(\left(x-5\right)^{10}=1\)

\(x-5=1\) hoặc \(x-5=-1\)

+) \(x-5=1\)

\(x=1+5\)

\(x=6\)

+) \(x-5=-1\)

\(x=-1+5\)

\(x=4\)

Vậy \(x=4;x=5;x=6\)

16 tháng 2 2022

a) 35 : 5 và (35 x 4) : (5 x 4)   

35:5= 7

(35 x 4) : (5 x 4) = 140 : 20 =7

=> 35 : 5  =  (35 x 4) : (5 x 4)            

b) 105 : 15 và (105 : 5) : (15 : 5)

105:15 =7

(105 : 5) : (15 : 5)= 7 : 3= 2 (dư 1)

=>105 : 15 > (105 : 5) : (15 : 5)

15 tháng 6 2015

a) x= 845/528

b)x = -7/5

c)x=-47/140

d)x= 43/1710

20 tháng 6 2016

mình viết đáp án luôn nhé

a,x=845/528

b,-7/5

c,-47/140

d,43/1710

chúc bạn làm bài thành công nhe!!@

các bạn nhớ chọn k đúng cho mình nhé

10 tháng 7 2023

`1, -2/9 xx 15/17 + (-2/9) xx 2/17`

`= -2/9 xx (15/17 + 2/17)`

`= -2/9 xx 17/17`

`=-2/9xx1`

`=-2/9`

__

`-5/3 xx 6/5 + (-7/9) xx 3/10`

`= -30/15 + (-21/90)`

`= -2 + (-7/30)`

`=-60/30 +(-7/30)`

`=-67/30`

__

`15/20 xx 7/5 + (-9/7) xx (-6/4)`

`=3/4 xx7/5 + (-9/7) xx(-6/4)`

`= 21/20 + 54/28`

`= 21/20 + 27/14`

`=417/140`

__

`-25/13 xx 5/19 + (-25/13) xx 14/19`

`=-25/13 xx (5/19 +14/19)`

`=-25/13 xx 19/19`

`= -25/13 xx 1`

`=-25/13`

__

`-7/13 xx 13/5 + (-9/7) xx 5/3`

`=-7/5 +(-15/7)`

`=-124/35`