a) 7 - ( 18 + x ) = - 15

18 + x = 7+ 15

18 + x = 22

x = 22 - 18

x = 4

vậy x= 4

Trl:

a) \(7-\left(18+x\right)=-15\)

\(\Rightarrow\left(18+x\right)=7-\left(-15\right)\)

\(\Rightarrow\left(18+x\right)=7+15\)

\(\Rightarrow\left(18+x\right)=22\)

\(\Rightarrow x=22-18\)

\(\Rightarrow x=4\)

b) \(\left(x-17\right)-\left(-3\right)=0\)

\(\Rightarrow\left(x-17\right)+3=0\)

\(\Rightarrow\left(x-17\right)=0-3\)

\(\Rightarrow\left(x-17\right)=-3\)

\(\Rightarrow x=-3+17\)

\(\Rightarrow x=14\)

-Để 159a235b chia hết cho cả 2,3,5 và 9 thì b phải bằng 0

-Để 159a2350 chia hết cho 3 và 9 

=>1+5+9+a+2+3+5 chia hết cho 3,9

=>25+a chia hết cho 3 và 9

=>a =2

Vậy a =2,b=0

\(3^x=\frac{9^{10}}{27^5}=243\)\(=3^5\)\(\Rightarrow x=5\)

Em lớp mấy

45782385 - 9936 + 5526367 = 51298816

Tk cho mk nhé ^-^

a. 12⁷ : 6⁷ = 2⁷

b. 27⁵ : 81³ = (3³)⁵ : (3⁴)³ = 3¹⁵ : 3¹² = 3³

c. 18³ : 9³ = 2³

d. 125³ : 25⁴ = (5³)³ : (5²)⁴ = 5⁹ : 5⁸ = 5

k cho mik nha !!!

1) He worked at night when he worked in the supermarket.

→ He used to work at night when he worked in the supermarket.

2) Did they watch TV in the past ?

→ Did they use to watch TV in the past?

3) She played badminton in her free time.

→ She used to play badminton in her free time.

4) They went swimming in the afternoon in 1990.

→ They used to go swimming in the afternoon in 1990.

5) He was a doctor in that hospital.

→ He used to be a doctor in that hospital.

☘ Perfect Answer ☘

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