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Ta có: \(\left(\dfrac{3}{5}+0.415-\dfrac{3}{200}\right)\cdot2\dfrac{2}{3}\cdot0.25\)

\(=\left(\dfrac{120}{200}+\dfrac{83}{200}-\dfrac{3}{200}\right)\cdot\dfrac{8}{3}\cdot\dfrac{1}{4}\)

\(=\dfrac{8}{3}\cdot\dfrac{1}{4}=\dfrac{8}{12}=\dfrac{2}{3}\)

13 tháng 7 2022

a) x=7-\dfrac{2}{5}+1,62=8,22
b) x=4 \dfrac{3}{5}+\dfrac{1}{5}-\dfrac{1}{2}=4 \dfrac{3}{10}
c) 2 x-x=\dfrac{3}{5}+\dfrac{4}{7}
x=\dfrac{41}{35}
d) x=3 \dfrac{1}{2}-\dfrac{5}{7}+\dfrac{1}{13}-0.25
x=2 \dfrac{223}{364}

 

 x=7-\dfrac{2}{5}+1,62=8,22
b) x=4 \dfrac{3}{5}+\dfrac{1}{5}-\dfrac{1}{2}=4 \dfrac{3}{10}
c) 2 x-x=\dfrac{3}{5}+\dfrac{4}{7}
x=\dfrac{41}{35}
d) x=3 \dfrac{1}{2}-\dfrac{5}{7}+\dfrac{1}{13}-0.25
x=2 \dfrac{223}{364}
 

a: \(\Leftrightarrow2x+\dfrac{7}{2}=\dfrac{16}{3}:\dfrac{11}{3}=\dfrac{16}{11}\)

=>2x=-45/22

hay x=-45/44

b: =>x/7=-1/28:1/4=-1/7

=>x=-1

10 tháng 3 2022

a)(7/2+2x).11/3=16/3

7/2+2x=16/3:11/3

7/2+2x=16/3.3/11

7/2+2x=16/11

2x=16/11-7/2

2x= -45/22

x= -45/22:2

x= -45/44

Vậy x= -45/44

b)x/7 +1/4= -1/28

x/7= -1/28-1/4

x/7= -2/7

=>x= -2

13 tháng 10 2021

a, \(\dfrac{3}{4}x=-\dfrac{9}{8}\)
x= \(-\dfrac{3}{2}\)
b, |x| + 0,25= 5,25
|x | = 5
=> x\(\in\){ +- 5}
Ko chắc đúng, kiểm tra trc khi làm

13 tháng 10 2021

\(\dfrac{2x-1}{3}=\dfrac{-5}{0.6}\)

\(\Leftrightarrow2x-1=-25\)

hay x=-12

HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023

\(\begin{array}{l}a)5{x^3} + {x^3} = (5 + 1){x^3} = 6{x^3}\\b)\dfrac{7}{4}{x^5} - \dfrac{3}{4}{x^5} = \left( {\dfrac{7}{4} - \dfrac{3}{4}} \right){x^5} = \dfrac{4}{4}{x^5} = {x^5}\\c)( - 0,25{x^2}).(8{x^3}) = ( - 0,25.8).({x^2}.{x^3}) =  - 2.{x^5}\end{array}\)

15 tháng 1 2022

\(a,\dfrac{-3}{4}x+1=\dfrac{5}{6}\\ \Rightarrow\dfrac{-3}{4}x=\dfrac{-1}{6}\\ \Rightarrow x=\dfrac{2}{9}\\ b,\left(2x-3\right)\left(x-5\right)=0\\ \Rightarrow\left[{}\begin{matrix}2x-3=0\\x-5=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=5\end{matrix}\right.\\ c,\dfrac{1}{2}-\left|x+1\right|=0,25\\ \Rightarrow\left|x+1\right|=0,25\\ \Rightarrow\left[{}\begin{matrix}x+1=0,25\\x+1=-0,25\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-0,75\\x=-1,25\end{matrix}\right.\)

a: =>-3/4x=-1/6

hay x=2/9

b: =>2x-3=0 hoặc x-5=0

hay x=3/2 hoặc x=5

c: =>|x+1|=1/4

\(\Leftrightarrow x+1\in\left\{\dfrac{1}{4};-\dfrac{1}{4}\right\}\)

hay \(x\in\left\{-\dfrac{3}{4};-\dfrac{5}{4}\right\}\)

HQ
Hà Quang Minh
Giáo viên
17 tháng 9 2023

a)

\(\dfrac{1}{2}{x^2}.\dfrac{6}{5}{x^3} = \dfrac{1}{2}.\dfrac{6}{5}.{x^2}.{x^3} = \dfrac{3}{5}{x^5}\);                                                   

b)

\(\begin{array}{l}{y^2}(\dfrac{5}{7}{y^3} - 2{y^2} + 0,25) = {y^2}.\dfrac{5}{7}{y^3} - {y^2}.2{y^2} + {y^2}.0,25)\\ = \dfrac{5}{7}{y^5} - 2{y^4} + 0,25{y^2}\end{array}\);

c)

\(\begin{array}{l}(2{x^2} + x + 4)({x^2} - x - 1) \\= 2{x^2}({x^2} - x - 1) + x({x^2} - x - 1) + 4({x^2} - x - 1)\\ = 2{x^4} - 2{x^3} - 2{x^2} + {x^3} - {x^2} - x + 4{x^2} - 4x - 4 \\= 2{x^4} - {x^3} + {x^2} - 5x - 4\end{array}\);                                                               

d)

\(\begin{array}{l}(3x - 4)(2x + 1) - (x - 2)(6x + 3) \\= 3x(2x + 1) - 4(2x + 1) - x(6x + 3) + 2(6x + 3)\\ = 6{x^2} + 3x - 8x - 4 - 6{x^2} - 3x + 12x + 6\\ = 4x + 2\end{array}\).

11 tháng 7 2017

d, 32%-0,25:x=-3/2/5

0,32-0,25:x=-3,4

-0,25:x=-3,4-0,32

-0,25:x=-3,72

x=-0,25:-3,72

x=25/372

11 tháng 7 2017

7/8+4/1/2:x=-13/40

0,875+4,5:x=-0,325

4,5:x=-0,325-0,875

4,5:x=-1,2

x=4,5:-1,2

x=-3,75

23 tháng 4 2017

9) \(\dfrac{x}{4}=\dfrac{9}{x}\)

Theo định nghĩa về hai phân số bằng nhau, ta có:

\(4\cdot9=x^2\\ 36=x^2\Rightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)

8)

\(x:\dfrac{5}{3}+\dfrac{1}{3}=-\dfrac{2}{5}\\ x:\dfrac{5}{3}=-\dfrac{2}{5}+\dfrac{1}{3}\\ x:\dfrac{5}{3}=-\dfrac{1}{15}\\ x=\dfrac{1}{15}\cdot\dfrac{5}{3}\\ x=\dfrac{1}{9}\)

7)

\(2x-16=40+x\\ 2x-x=40+16\\ x\left(2-1\right)=56\\ x=56\)

6)

\(1\dfrac{1}{2}+x=\dfrac{3}{2}-7\\ \dfrac{3}{2}+x=\dfrac{3}{2}-7\\ \dfrac{3}{2}-\dfrac{3}{2}=-7-x\\ -7-x=0\\ x=-7-0\\ x=-7\)

5)

\(3\dfrac{1}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\\ \dfrac{7}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\\ \dfrac{1}{2}x=\dfrac{7}{2}-\dfrac{2}{3}\\ \dfrac{1}{2}x=\dfrac{17}{6}\\ x=\dfrac{17}{6}:\dfrac{1}{2}\\ x=\dfrac{17}{3}\)

4)

\(x\cdot\left(x+1\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)

3)

\(\left(\dfrac{2x}{5}+2\right):\left(-4\right)=-1\dfrac{1}{2}\\ \left(\dfrac{2x}{5}+2\right):\left(-4\right)=-\dfrac{3}{2}\\ \dfrac{2x}{5}+2=-\dfrac{3}{2}\cdot\left(-4\right)\\ \dfrac{2x}{5}+2=6\\ \dfrac{2x}{5}=6-2\\ \dfrac{2x}{5}=4\\ 2x=4\cdot5\\ 2x=20\\ x=20:2\\ x=10\)

2)

\(\dfrac{1}{3}+\dfrac{1}{2}:x=-0,25\\ \dfrac{1}{3}+\dfrac{1}{2}:x=-\dfrac{1}{4}\\ \dfrac{1}{2}:x=-\dfrac{1}{4}-\dfrac{1}{3}\\ \dfrac{1}{2}:x=-\dfrac{7}{12}\\ x=\dfrac{1}{2}:-\dfrac{7}{12}\\ x=-\dfrac{6}{7}\)

1)

\(\dfrac{4}{3}+x=\dfrac{2}{15}\\ x=\dfrac{2}{15}-\dfrac{4}{3}x=-\dfrac{6}{5}\)

16 tháng 1 2019

2.a)\(\dfrac{3\text{x}-2}{2}\)=\(\dfrac{1-2\text{x}}{3}\)

<=>\(\dfrac{9\text{x}-6}{6}\)=\(\dfrac{2-4\text{x}}{6}\)

<=>9x-6=2-4x

<=>9x+4x=2+6

<=>13x=8

<=>x=\(\dfrac{8}{13}\)

16 tháng 1 2019

1.a)2(x-0,5)+3=0,25(4x-1)

<=>2x-1+3=x-1phần4

<=>2x-x=-1/4+1-3

<=>x=-3/4