a) ( 2x + 1 )( y - 5 ) = 12

=>2x+1:y-5 là Ư(12)

12=1.12=2.6=3.4

do 2x+1 lẻ =>2x+1=1 hoặc 2x+1=3

vậy (x,)=(0,17);(1,9)

b)4n - 5 chia hết cho 2n - 1

<=>2(2n-1)-3 chia hết 2n-1

=>3 chia hết 2n-1

=>2n-1 thuộc {1,-1,3,-3}

=>n thuộc {1;2}

c)ta có:99=11.9

B chia hết 99=> B chia hết 11 và 9

=>(x+y+3) chia hết 9=>x+y=6 hoặc x+y=15

x-y=9 (loại) hoặc y-x=2

y-x=2 và x+y=6 =>y=4;x=2

y-x=2 và x+y=15 (loại)

vậy y=4;x=2 thì 6224427 chia hết 99

tui mua

Fill in each gap with a suitable preposition.

1. Don't laugh ....... her or she 'll get angry.

2. It's very difficult to find work ...... the moment.

3. In many ways you take ........ your mother.

4. Parents are naturally anxious......... their children .

5. I'm sure you will succed .......this entrance test .

6. We try to prevent people ........... littering.

7. I'm going to complain to the principal............ this.

8. This computer is still ............ guarantee.

9. Money is not essential .............. happiness.

10. She is ............ far the best teacher I have ever had.

HELP ME !!

nửa chu vi là

216:2=108

chiều rộng hình chữ nhật là:

108:[4+5]x4=48

Use the correct form of the words in the brackets

1. Our washing machine has stopped working. I'll phone the .............. ( electric )

2. ........., the typhoon didn't cause any damage to the village.(lucly)

3. All tourists enjoy ......... atmosphere in VietNam.( peace )

4. The hurricane brought total ......... to the city.( Destroy )

5. ........... , the meat associated with Easter is lamb . ( Traditon )

1245 nha bnj mỏi tay quá ko làm rõ được