a) 75 : ( x - 18 ) = 5² = 25

=>       x - 18 = 3

=>       x = 21

b) 740 : ( x - 10 ) = 10² - 2 x 13

    740 : ( x - 10 ) = 100 - 26 = 74

=>           x - 10 = 10

=>            x = 20

c) ( 2x - 5 )³ = 8 = 2³

=>  2x - 5 = 2

=>  2x = 7

=>     x= 7/2

d) ( 15 - 6x ) x 3⁵ = 3⁶

=> ( 15 - 6x ) = 3⁶ : 3⁵ = 3

=>   6x = 12

=>     x = 2

1+1= ??????

Bài 2

a) x=5

b)x=1

75 - 4 . ( x + 1 ) = 71

 4x + 4 = 4

4x = 0

=> x = 0

2^x . 2⁵ = 64

2^x . 2⁵ = 2⁷

=> x + 5 = 7

=> x = 2

9^{x - 1} = 9

=> 9^{x - 1} = 9¹

=> x - 1 = 1 => x = 2

Câu a:

2.(x + 2/5) + 1 1 /4 = 11/20

2x + 4/5 + 5/4 = 11/20

2x = 11/20 - 5/4 - 4/5

2x = 11/20 - 25/20 - 16/20

2x = -30/20

2x = -3/2

x = -3/2 : 2

x = - 3/4

Vậy x = - 3/4

Câu b:

x - 1 1/8 - 2/3x - 5/6x = 75%

(x - 2/3x - 5/6x) = 75% + 1 1/8

x (1 - 2/3 - 5/6) = 3/4 + 9/8

x (6/6 - 4/6 - 5/6) = 6/8 + 9/8

x.(-1/2) = 15/8

x = 15/8 : (-1/2)

x = 15/8 x (-2)

= -15/4

a) \(2.\left(x+\frac{2}{5}\right)+1\frac{1}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)+\frac{5}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)=\frac{-7}{10}\)

\(x+\frac{2}{5}=\frac{-7}{20}\)

\(x=\frac{-13}{20}\)

Vậy \(x=\frac{-13}{20}\)

b)\(x-1\frac{1}{8}-\frac{2}{3}x-\frac{5}{6}x=75\%\)

  \(\left(x-\frac{2}{3}x-\frac{5}{6}x\right)-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x=\frac{15}{8}\)

\(x=\frac{-15}{4}\)

Vậy \(x=\frac{-15}{4}\)

3^4 . 9 .3^x = 3^7

3^4 . 3^2 . 3^x = 3^7

3^6 . 3^x = 3^7

3^x = 3

x = 1

4^x . 4^1 = 16

4^x = 16 : 4

 4^x =4

=> x=1

5^x : 5 = 25

5^x = 25 . 5 =125

=> x = 3