Bai 1: mot khu dat HCN co chu vi la 2km5hm, chieu dai gap 4 lan chieu rong.Tinh dien tich khu dat do may met vuong ? may ha?

Bai 2: Nam nay tong so tuoi cua 2 bo con la 40 tuoi, biet rang sau 4 nam nua thi tuoi con bang 1 phan 3 tuoi bo. Hoi nam nay bo bao nheu tuoi , con bao nhieu tuoi?

Bai 3: Thuong cua 2 so la 0,6. Hieu cua 2 so la 52. Tim hai so do?

Bai 4:Tinh nhanh

a) 35x18-9x70+100  

b) 4x 113x 25-5x 112 x 20 

c) { 20 +  21 +22 +23+24+25}x{16-2×8}

bai 1:tim n thuoc n de:3(n+2) chia het cho n-2

bai 2chng minh rang cac so sau la cac so nguyen to cung nhau

a) 18n+3 va 21n+4

b)2n+1va3n+1

bai 3:tim hai so biet tong hai so la 90 va uoc chung lon nhat la 15

bai 4:tim so tu nhien n lon nhat co 3 chu so sao cho n :15 du 9va n:35 du 29

bai 5:tim uoc chung lon nhat cua cac so sau:

a)18n+3 va 21n+4

b)9n+13 va 3n+4

bai 6:chung minh: voi moi a,b thuoc nta co

UCLN(a,b)=UCLN (5a+2b,7a+3b)

AI DUNG TRUOC 9H MINH SE TICH CHO.THANHK YOU VERY MUCH!

bai 1 : Tim hieu cua hai so, biet rang so lon them 735 don vi va so ben them 449 don vi thi duoc hieu moi la 2000.

Bai 2 : Khi thuc hien phep tru hai so, mot ban da so y viet sai nhu sau : o so bi tru co hai chu socuoi cung la 35 da viet thanh 53 nen phep tru sai co ket qua la 1234. Tim hieu dung cu ahia so do.

Bai 3 : TIm mot so biet rang so do cong voi so lon nhat co ba chu so khac nhau roi cong tiep voi so be nhat co bon chu so khac nhau thi duoc so be nhat co nam chu so.

Bai 4 ; Cho ba chu so tu nhieu A ; B ; C. Biet rang tong cua A va B la 492 ; tongg cua B va C la 936 ; tong cua C va A la 714. Tim ba so do.

Bai 5 : HAi kho chu atat ca 2500 tan thoc. Sau khi lay ra o moi kho so tan thoc nhu sau. thi kho thu nhat con 800 tan va kho thu hai con 500 tan. Hoi luc dau moi kho chua bao nhieu tan thoc?