\(a,\dfrac{x}{7}=\dfrac{6}{21}\Rightarrow x.21=7.6=42\\ \Rightarrow x=2\\ b,\dfrac{1}{2}=\dfrac{x}{12}\Rightarrow1.12=2.x=12\\ \Rightarrow x=6\\ c,\dfrac{-7}{6}=\dfrac{x}{12}\Rightarrow-7.12=6.x=-84\\ \Rightarrow x=-14\)

mình đang cần gấp, giúp mình với ạ

câu d là 6 phần mấy đấy ạ?

a. 5 - 3(x + 4) = -1

⇔ 5 - 3x - 12 = -1

⇔ 3x = -1 - 5 + 12

⇔ 3x = 6

⇔ x = 2

\(d,2x^2-3=5\)

\(\Leftrightarrow2x^2=8\)

\(\Leftrightarrow x^2=4\)

\(\Leftrightarrow x=\pm2\)

\(e,x\left(2x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}2x=1\\x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=0\end{matrix}\right.\)

a)\(=>3\left(x+4\right)=6=>x+4=2=>x=-2\)

b)\(=>x-1-x-2=0\)

\(=>-3=0\left(vl\right)\) => x ko tồn tại

 58/7 - (31/9 + 30/7)                  
= 58/7 - 31/9 - 30/7
= (58/7 - 30/7) - 31/9
= 28/7- 31/9
= 4 - 31/9 = 36/9 - 31/9
= 5/9

478/19÷(-5/4)-668/19÷(-5/4)
=(478/19-668/19):(-5/4)
=-10 . (-4/5)
=8

a: x^3=7^3

=>x^3=343

=>\(x=\sqrt[3]{343}=7\)

b: x^3=27

=>x^3=3^3

=>x=3

c: x^3=125

=>x^3=5^3

=>x=5

d: (x+1)^3=125

=>x+1=5

=>x=4

e: (x-2)^3=2^3

=>x-2=2

=>x=4

f: (x-2)^3=8

=>x-2=2

=>x=4

h: (x+2)^2=64

=>x+2=8 hoặc x+2=-8

=>x=6 hoặc x=-10

j: =>x-3=2 hoặc x-3=-2

=>x=1 hoặc x=5

k:

9x^2=36

=>x^2=36/9

=>x^2=4

=>x=2 hoặc x=-2

l:

(x-1)^4=16

=>(x-1)^2=4(nhận) hoặc (x-1)^2=-4(loại)

=>x-1=2 hoặc x-1=-2

=>x=3 hoặc x=-1

a) x-2∈ Ư(3x-13)= 3x-13⋮x-2

=3x-6-7⋮x-2=(x-2)(x-2)(x-2)-7⋮x-2

=> x-2∈Ư(-7)={7;1;-7;-1}

Nếu

x-2=7 => x=7+2=> x=9

x-2=1=>x=1+2=>x=3

x-2=-7=>x=(-7)+2=>x=-5

x-2=-1=>x=(-1)+2=>x=1

Vậy x ∈ {9;3;-5;1}

b) \(-15\left(x-2\right)+7\left(3-x\right)=7\)

\(\Leftrightarrow-15x+30+21-7x=7\\ \Leftrightarrow-22x+51=7\\ \Leftrightarrow-22x=7-51\\ \Leftrightarrow-22x=-44\\ \Leftrightarrow x=2\)

Vậy ...

c) \(\left(2x+1\right)^2=6\)

\(\Leftrightarrow4x^2+4x+1=6\\ \Leftrightarrow4x^2+4x+1-6=0\\ \Leftrightarrow4x^2+4x-5=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{\sqrt{6}+1}{2}\\x=\dfrac{\sqrt{6}-1}{2}\end{matrix}\right.\)

Vậy ...

d) \(4\left(5-x\right)-3\left(1-x\right)=3^2\)

\(\Leftrightarrow20-4x-3+3x=9\\ \Leftrightarrow17-x=9\\ \Leftrightarrow-x=9-17\\ \Leftrightarrow-x=-8\\ \Leftrightarrow x=8\)

Vậy ...

a) x=-2

b) x=12; x=-2

c) x=12; x=-6

Lắm phần c,d , b quá

15 chia hết cho 2x+1 thì x= 1, x=4 và x=7 (nếu cả số âm nữa thì tự tìm nhé)

10 chia hết cho 3x+1 thì x=0, x=3 (nếu cả số âm nữa thì tự tìm nhé)

(7-x)-(25+7)=25 thì x=-36

6 chi hết cho x-1 thì x=2: x=3: x=4: x=7 (nếu cả số âm nữa thì tự tìm nhé)

5 chia hết cho x+1 thì x=0; x=4  (nếu cả số âm nữa thì tự tìm nhé)

e) x=0: x=1: x=3: x=9

f) x=1

g) x=0: x=2; x=4; x=14

z) x=0: x=1: x=4: x=9

vai cut

Bài 1:

a) 2^|x-1| = 2⁴.64

=> 2^|x-1|= 2¹⁰

=> |x-1|=10

=> \(\left[{}\begin{matrix}x-1=10\\x-1=-10\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=11\\x=-9\end{matrix}\right.\)

Vậy...

b)(3x-1)⁴=16

=> (3x-1)⁴=2⁴

=> 3x - 1=2

=> 3x = 3

=> x=1

Vậy...

c) (2x+1)⁴=(2x+1)⁶

=> (2x+1)⁴ - (2x+1)⁶=0

=> (2x+1)⁴.[1 - (2x+1)² ] = 0

=> \(\left[{}\begin{matrix}\left(2x+1\right)^4=0\\1-\left(2x+1\right)^2=0\end{matrix}\right.\)

+) (2x+1)⁴=0⁴

=> 2x+1=0

=> 2x = -1

=> x= \(\frac{-1}{2}\)

+) 1 - (2x+1)²=0

=> (2x+1)² = 1

=> \(\left[{}\begin{matrix}2x+1=1\\2x+1=-1\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)

Vậy...

d) x¹³=27.x¹⁰

=> x³=3³

=> x=3

e)2^x+2^x+3=144

=> 2^x(1+8)=144

=> 2^x= 16 = 2⁴

=> x=4

Bài 2:

a) Hình như đề bài là thế này:

CMR: 5⁵-5⁴+5³ chia hết cho 7

Xét 5⁵-5⁴+5³

=5³(5²-5+1)

=5³. 21

Mà 21\(⋮\)7 => 5³.21 chia hết cho 7 hay 5⁵-5⁴+5³

Vậy...

b) Xét 7⁶+7⁵-7⁴

= 7⁴(7²+7-1)

=7⁴.55

Mà 55 \(⋮\)11 => 7⁴.55 chia hết cho 11 hay 7⁶+7⁵-7⁴ chia hết cho 7

Vậy...

Bài 1:

b) \(\left(3x-1\right)^4=16\)

=> \(\left(3x-1\right)^4=2^4\)

=> \(3x-1=2\)

=> \(3x=2+1\)

=> \(3x=3\)

=> \(x=3:3\)

=> \(x=1\)

Vậy \(x=1.\)

Bài 2:

\(5^5-5^4+5^3\)

\(=5^3.\left(5^2-5+1\right)\)

\(=5^3.21\)

Vì \(21⋮7\) nên \(5^3.21⋮7.\)

=> \(5^5-5^4+5^3⋮7\left(đpcm\right).\)

b) \(7^6+7^5-7^4\)

\(=7^4.\left(7^2+7-1\right)\)

\(=7^4.55\)

Vì \(55⋮11\) nên \(7^4.55⋮11\).

=> \(7^6+7^5-7^4⋮11\left(đpcm\right).\)

Chúc bạn học tốt!

a) \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}\)

\(\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{3}{5}\)

\(x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}\)

b) \(\dfrac{39}{7}:x=13\)

\(x=\dfrac{\dfrac{39}{7}}{13}=\dfrac{3}{7}\)

c) \(\left(\dfrac{14}{5}x-50\right):\dfrac{2}{3}=51\)

\(\dfrac{14}{5}x-50=51\cdot\dfrac{2}{3}=34\)

\(\dfrac{14}{5}x=34+50=84\)

\(x=\dfrac{84}{\dfrac{14}{5}}=30\)

d) \(\left(x+\dfrac{1}{2}\right)\left(\dfrac{2}{3}-2x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\\dfrac{2}{3}-2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)

e) \(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{12}\)

\(\dfrac{1}{6}x=\dfrac{5}{12}\)

\(x=\dfrac{5}{12}:\dfrac{1}{6}=\dfrac{5}{2}\)

g) \(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\dfrac{11}{5}-\dfrac{3}{7}=-2\)

\(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)

\(x\cdot\dfrac{44}{7}+\dfrac{3}{7}=-\dfrac{11}{7}:\dfrac{11}{5}=-\dfrac{5}{7}\)

\(\dfrac{44}{7}x=-\dfrac{5}{7}-\dfrac{3}{7}=-\dfrac{8}{7}\)

\(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)

h) \(\dfrac{13}{4}x+\left(-\dfrac{7}{6}\right)x-\dfrac{5}{3}=\dfrac{5}{12}\)

\(\dfrac{25}{12}x-\dfrac{5}{3}=\dfrac{5}{12}\)

\(\dfrac{25}{12}x=\dfrac{5}{12}+\dfrac{5}{3}=\dfrac{25}{12}\)

\(x=1\)

Mỏi tay woa bn làm nốt nha!!

1) 2. I2x-3l = 1/2

         |2x-3| =1/2:2

          |2x-3| =1/4

        =>2x-3 =1/4      hoặc    2x-3 =-1/4

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

            2x      =13/4                2x     =11/4

               x      =13/4:2              x     =11/4:2

               x       =13/8                x     =11/8

vậy x=13/8 hoặc 11/8

tich dung cho minh nhe