ban co the giai thich cho minh ro hon duoc ko,co phai cau nhom 3 cai vao voi nhau dung ko

What is the place were you born

Banj hỏi chỗ nào vậy

S = (1 + 2) + (2^2 + 2^3) + (2^4 + 2^5) + (2^6 + 2^7)

S=  1.1 + 2.1 + 2^2.1+2^2.2+ 2^4.1+2^4.2 + 2^6.1 + 2^6.2

S = 1.(1+2) + 2^2.(1+2) + 2^4.(1+2) + 2^6.(1 + 2)

S = 1.3 + 2^2.3 + 2^4.3 +2^6.3

S = 3.(1+2^2+2^4+2^6)

S chia hết cho 3 

Tet is a national and family festival. It is an occasion for family gathering and for every Vietnamese to have time thinking about the last year and the next year .At Tet ,spring fairs are organized ,street and public buildings are brightly decorated and almost all shops are crowded with people shopping for Tet .At home ,everything is tidied ,special food is cooked ,offerings of food ,fresh water ,flowers and betel are displayed on the family altar with burning joss-sticks scenting the air. First footing is made when the lucky visitors comws and children are given lucky money wrapped in a red envelope .Tet is also a time for peace and love.During Tet ,children often behave well and friends,relatives and neighbors give each other best wishes for the Ney Year .Besides,at Tet ,you shouldn’t give anyone a cat as a present or bring a black cat into the house while dogs are lucky animal because they barking a sound like “gold”. You shouldn’t eat shrimps because people tjink this can make you not suceed .At Tet ,people in Viet Nam often throw salt and ricw on the road, they also buy and give red fruits for happiness.

mệt quá

=> - 620 - 80

= -700

Gọi số học sinh của trường đó là x

(Điều kiện: x € N,900<x<999[vì đó là số học sinh lớn hơn 900 và có 3 chữ số]

Vì số học sinh đó khi xếp hàng 3,4,5 thì vừa đủ nên

=> \(\left\{{}\begin{matrix}X:3\\x:4\\x:5\end{matrix}\right.\)

=>x € BC(3,4,5)

Ta có :3=3.

4=2²

5=5

BCNN(3,4,5)=3.2².5=60

BC(3,4,5)=B(60)={0;60;120;180;240;...}

Mà 900<x<999

=>x=960

Vậy trường đó có 960 học sinh

Do số đó bằng 19 lần tổng các chữ số của nó nên số đó chia hết cho 19
Để số đó là số nguyên tố và chia hết cho 19 thì số đó là 19
Thử lại 19=19 x (1+9)=19 x 10 = 190 (vô lý)
Vậy không thể tìm được số đó

Hihi