a) \(3x-18.28:14=308\)

\(=>3x-36=308\)

\(=>3x=344\)\(\)

\(=>x=\frac{344}{3}\)

\(\)b)\(38+\left|x\right|=\left(-12\right)+65\)

\(=>38+\left|x\right|=53=>\left|x\right|=15=>\orbr{\begin{cases}x=15\\x=-15\end{cases}}\)

c)\(15+3.\left(x-1\right):5=30\)

\(=>15+3.\left(x-1\right)=150\)

\(=>3.\left(x-1\right)=135\)

\(x-1=45=>x=46\)

d) \(5.\left(7-3x\right)+7.\left(2+2x\right)=1\)

\(=>35-15x+14+14x=1\)

\(=>49-x=1=>x=48\)

e)\(3.\left(x-7\right)=21\)

\(=>x-7=7=>x=14\)

g)\(\left[\left(6x-72\right):2-84\right]:28=5628\)

\(\left(6x-72\right):2-84=157584\)

\(\left(6x-72\right):2=157668\)

\(6x-72=315336\)

\(6x=315408=>x=52568\)

h)\(123-5\left(x+4\right)=28\)

\(5.\left(x+4\right)=95\)

\(x+4=19=>x=15\)

p)\(14.\left(x-3\right)-138=73\)

\(14.\left(x-3\right)=211\)

\(x-3=\frac{211}{14}=>x=\frac{253}{14}\)

\(t\)

\(\left|x\right|-5=2\)

\(\left|x\right|=7=>\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)

v)\(4x-72=\left|100-8.25\right|\)

\(4x-72=\left|-100\right|\)

\(4x-72=100=>4x=172=>x=43\)

cậu có thể tham khảo bài làm trên đây ạ, chúc cậu học tốt ^^

6) \(2\left(x-8\right)=2^2\)

\(\Rightarrow x-8=2^2:2\)

\(\Rightarrow x-8=2\)

\(\Rightarrow x=2+8\)

\(\Rightarrow x=10\)

tíc mình nha

5) 14 chia hết cho 2x+3

=>2x+3 thuộc ước 14

mà Ư(14)={1,2,7,14}

ta có

vậy x=0

219-7(x+1)=100

      7(x+1)=219-100

      7(x+1)=119

         x+1 =119:7

         x+1=17

         x    =17-1

         x    =16

a. 9x² - 6x - 3 = 0

<=> 3(3x² - 2x - 1) = 0

<=> 3(3x² - 3x + x - 1) = 0

<=> \(3\left[3x\left(x-1\right)+\left(x-1\right)\right]=0\)

<=> 3(3x + 1)(x - 1) = 0

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

b. (2x + 1)² - 4(x + 2)² = 9

<=> (2x + 1)² - \(\left[2\left(x+2\right)\right]^2=9\)

<=> (2x + 1 - 2x - 4)(2x + 1 + 2x + 4) = 9

<=> -3(4x + 5) = 9

<=> 4x + 5 = -3

<=> 5 + 3 = -4x

<=> -4x = 8

<=> -x = 2

<=> x = -2

a) \(\Leftrightarrow\left(9x^2-6x+1\right)-4=0\)

\(\Leftrightarrow\left(3x-1\right)^2-4=0\)

\(\Leftrightarrow3\left(x-1\right)\left(3x+1\right)=0\)

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

b) \(\Leftrightarrow4x^2+4x+1-4x^2-16x-16=9\)

\(\Leftrightarrow12x=-24\Leftrightarrow x=-2\)

c) \(\Leftrightarrow3x^2-6x+3-3x^2+15x=21\)

\(\Leftrightarrow9x=18\Leftrightarrow x=2\)

d) \(\Leftrightarrow x^2+6x+9-x^2-4x+32=1\)

\(\Leftrightarrow2x=-40\Leftrightarrow x=-20\)

a)\(2.x-138=8.9\)

\(2.x-138=72\)

\(2.x=72+138\)

\(2.x=210\)

\(x=210\div2\)

\(x=105\)

b)\(\left\{\left(6x-72\right)\div2-84\right\}.28=5628\)

\(\left(6x-72\right)\div2-84=201\)

\(\left(6x-72\right)\div2=285\)

\(6x-72=570\)

\(6x=642\)

\(x=107\)

c)\(420+65.4=\left(x+175\right)\div5+30\)

\(420+260=\left(x+175\right)\div5+30\)

\(680=\left(x+175\right)\div5+30\)

\(650=\left(x+175\right)\div5\)

\(3250=x+175\)

\(3075=x\)

a) 2 * x - 138 = 72

    2 * x          = 72 + 138

    x                = 210 \ 2

    x                = 105

Mk thay x=y nha!!!

a)2xy-138=8x9

2xy-138=72

2xy=72+138

2xy=210

y=210:2

y=105

b){(6xy-72):2-84)}x28=5628

{(6xy-72):2-84)}x28=5628

{(6xy-72):2-84=201

{(6xy-72):2=285

(6xy-72)=570

6y=570+72

6y=642

=>y=107

c)420+65x4=(y+175):5+30

680=(y+175):5+30

650=(y+175):5

3250=y+175

y=3250-175

y=3075

1) 6^x+2=216=6³

=>x+2=3

=>x=1

2)7²-(15+x)=5.2²

49-15-x=5.4

34-x=20

x=14

3)[(6x-72):2-84].28=5628

(3x-36-84).28=5628

3x-36-84=201

3x-120=201

3x=321

x=107

4)3^x-2.4=324

3^x-2=81=3⁴

=>x-2=4

x=6

\(6^{x+2}=216\Leftrightarrow6^x=216:6^2=6;x=1\)\(7^2-\left(15+x\right)=5.2^2\Leftrightarrow49-\left(15+x\right)=20\)

\(15+x=49-20=29;x=14\)

1)6^x+2=216

6^x+2=6³

=>x+2=3

x=3+2

x=5

2)7²-(15+x)=5.2²

49 -(15+x)=5.4

49 -(15+x)=20

15+x=49-20

15+x=29

x=29-15

x=14

3)[(6x-72):2-84].28=5628

(6x-72):2-84=5628:28

(6x-72):2-84=201

(6x-72):2=201+84

(6x-72):2=285

6x-72=285.2

6x-72=570

6x=570+72

6x=642

x=642:6

x=107

4)3^x-2.4=324

3^x-2=324:4

3^x-2=81

3^x-2=3⁴

=>x-2=4

x=4+2

x=6

a) Xem lại đề.

b) 5. (x - 3)² + 17 = 142

5. (x - 3)² = 142 - 17

5. (x - 3)² = 125

(x - 3)² = 125 : 5

(x - 3)² = 25

(x - 3)² = 5² (cùng số mũ)

⇒ x - 3 = 5

x = 5 + 3 = 8

c) [(6x - 72) : 2 - 84] . 28 = 5628

[(6x - 72) : 2 - 84] = 5628 : 28

[(6x - 72) : 2 - 84] = 201

(6x - 72) : 2 = 201 + 84

(6x - 72) : 2 = 285

6x - 72 = 285. 2

6x - 72 = 570

6x = 570 + 72

6x = 642

x = 642 : 6

x = 107