a,  2 x - 15 = 17

⇒ 2 x = 2 = 2 2 ⇒ x = 1

b,  7 x - 11 3 = 2 5 . 5 2 + 200

⇒ 7 x - 11 3 = 1000 = 10 3

⇒ 7x – 11 =10

⇒ 7x = 21

⇒ x = 3

a. 7x-2x=6¹⁷:6¹⁵ + 44:11

=> 5x=6² + 4

=> 5x=36 + 4

=> 5x=40

=> x=40:5

=> x=8

b. 2^x.(2²)²=(2³)²

=> 2^x.2⁴=2⁶

=> 2^x=2⁶:2⁴

=> 2^x=2²

=> x=2.

c. Theo đề => \(x\in BC\left(5,7\right)\)

Ta có: 5=5; 7=7

=> BCNN(5, 7)=5.7=35

=> \(x\in BC\left(5,7\right)=B\left(35\right)=\left\{0;35;70;105;140;175;210;245;280;315;...\right\}\)

Mà x < 300

Vậy x thuộc { 0; 35; 70; ...; 245; 280 }.

A, 89 -(73-x)=20

=> 73 - x = 89 - 20

=> 73 - x = 69

=> x = 73 - 69

=> x = 4

B, 7x - 2x = 6¹⁷:6¹⁵ + 44:11

=> ( 7 - 2 ) x = 36 + 4

=> 5x = 40

=> x = 8

C, x - [ 42+(-28)]=-8

=> x - 14 = - 8

=> x = - 8 + 14

=> x = 6

D, 62 - (2x-3):3=23

=> ( 2x - 3 ) : 3 = 62 - 23

=> ( 2x - 3 ) : 3 = 39

=> 2x - 3 = 117

=> 2x = 120

=> x = 60

E, 4(x-3)=7² - 1¹⁰

=> 4 ( x - 3 ) = 49 - 1

=> 4 ( x - 3 ) = 48

=> x - 3 = 12

=> x = 15

tìm số tự nhiên x biết

a, 2^x - 15 =17

=> 2^x = 17 + 15 = 32

=> 2^x = 2⁵

=> x = 5

b, ( 7x - 11)³ = 2⁵ x 5²+200

=> ( 7x - 11 )³ = 32 . 25 + 200

=> ( 7x - 11 )³ = 1000

=> ( 7x - 11 )³ = 10³

=> 7x - 11 = 10

=> 7x = 10 + 11 = 21

=> x = 21 : 7 = 3

a) \(5x+x=39-3^{11}:3^9\)

\(6x=39-3^2\)

\(x=30:6\)

\(x=5\)

vậy \(x=5\)

b) \(7x-x=5^{21}:5^{19}+3.2^2-7^0\)

\(6x=5^2+12-1\)

\(6x=36\)

\(x=6\)

vậy \(x=6\)

câu c tương tự nha

a) x=5,b)x=6 ,c)x=8 nha mình tự làm đấy

a ) 5 x + x = 3 9 − 3^11:3^9

6 x = 39 − 3^2

x = 30:6

x = 5

vậy x = 5

b ) 7 x − x = 5^21:51^9 + 3.2^2 − 7^0

6 x = 5^2 + 1 2 − 1

6 x = 36

x = 6

v ậ y x = 6

câu C làm tương tự nha bn @!!!!!!

a)

 \(\left(2x-15\right)^5=\left(2x-15\right)^3\\ \Leftrightarrow\left(2x-15\right)^5-\left(2x-15\right)^3=0\\ \Leftrightarrow\left(2x-15\right)^3.\left[\left(2x-15\right)^2-1\right]=0\\ \Leftrightarrow\left[{}\begin{matrix}2x-15=0\\\left(2x-15\right)^2-1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}2x-15=0\\\left(2x-15-1\right).\left(2d-15+1\right)=0\end{matrix}\right.\\\Leftrightarrow\left[{}\begin{matrix}2x-15=0\\2x-16=0\\2x-14=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{15}{2}\\x=8\\x=7\end{matrix}\right. \)

b) \(\left(7x-11\right)^3=\left(-3\right)^2.15+208\\ \Leftrightarrow\left(7x-11\right)^3=343=7^3\\ \Leftrightarrow7x-11=7\\ \Leftrightarrow x=\dfrac{18}{7}\)