D = 6a5b chia hết cho 18 nên 6a5b sẽ cũng chia hết cho 2 , 9 ( 2 và 9 là số nguyên tố )

Mà 6a5b chia hết cho 2 nên b = 0 ; 2 ; 4 ; 6 ; 8

Suy ra chia hết cho 9 = 6 + a + 5 + b sẽ chia hết cho 9 ( b = 0;2;4;6;8)

Nếu b = 0 thì a = 7 ( thỏa mãn )

Nếu b =2 thì a = 5 (thỏa mãn )

Nếu b= 4 thì a = 3 ( thỏa mãn )

Nếu b = 8 thì a = 8 ( thỏa mãn )

\(để\) \(\overline{6a5b}⋮18=>\overline{6a5b}⋮2,9\)

\(để\) \(\overline{6a5b}⋮2=>b⋮2=>b=\left\{0,2,4,6,8\right\}\)

\(để\) \(\overline{6a5b}⋮9=>\left(6+a+5+b\right)⋮9\)\(=>11+a+b⋮9\)

\(a+b\le11+a+b\le11+9+9=29\)

\(ma11+a+b⋮9=>11+a+b=\left\{0,9,18,27\right\}\)

\(=>a+b=\left\{7,16\right\}\)

nếu a+b=7

ta có:b=0=>a=7

b=2=>a=5

b=4=>a=3

b=6=>a=1

nếu b+a=16

ta có: b=8=>a=8

b=6=>a=10(loại)

b=4=>a=12(loại)

b=2=>a=14(loại)

b=0=>a=16(loại)

Vậy....

1, How many windows are there in the classroom?

2, How many telephones are there in the house?

3, How many computers are there in our school?

4, How many bookshelves are there in the livingroom?

5, How many teachers are there in our school?

6, How many books are there in your bag?

7, How many students are there in yourschool?

8, How many lamps are there in the living room?

Mỏi tay quá.

k mk nha.

#ngố

1. How many windows are there in the classroom ?

2. How many telephones are there in the house ?

3. How many computers are there in our school ?

4. How many bookshelves are there in the living room ?

5. How many teachers are there in our school ?

6. How many books are there in your school bag ?

7. How many students are there in our school ?

8. How many lamps are there in the living room ?

                                                          Chúc bạn học tốt ! ( nhớ tk cho mk nhé ! )

làm ơn ik, bik câu nào làm câu đó giúp mik ik ><

(27.2⁶.625):(5³.64.3²)

=(3³.2⁶.5⁴):(5³.2⁶.3²)

=3.5=15

\(\frac{2^{13}+2^5}{2^{10}+2^2}=\frac{2^5.\left(2^8+1\right)}{2^2.\left(2^8+1\right)}=\frac{2^5}{2^2}=2^3\)

/s/:books, parents, students,baskets, lamps, desks.

/z/:boards, engineers, doors, stools, armchairs, tables, teachers, years, window.

/iz/:classes, couches, telephones, benches, bookcases.

k nha

km sao  đổi được m³

mik ko bik, cô mik in đề như z mà b

a, 125n=5⁴

5³n=5³.5

suy ra n=5

3³n-3⁴=2⁵-5

3³n-3³.3=27

3³(n-3)=27

3³(n-3)=3³

suy ra n-3=1

n=4

7^2x+1-98=105

49x+1-98=105

49x+1=105+98

49x+1=203

49x=203-1

49x=202

x=202:49

x=4,122...

Vay x=4,122...