muon tim tong cac so hang ta lam the nao ?

tra loidung minh tick cho

tong hai so gap 4 lan so hang thu nhat , so hang thu hai = 72 tim so hang thu nhat .Ve so do doan thang

lam loi giai nhe cac ban

bai 1 

cho tong : S = 5 + 8 + 11 +14 = ....

a) tim so hang thu 100 cua tong

b) tinh tong 100 so hang dau tien

bai 2

cho tong : S = 7 + 12 + 17 + 22 + .......

a) tim so hang thu 50 cua tong

b) tinh tong 50 so hang dau tien

bai 3 

tinh tong cua tat ca cac so hang tu  nhien x , biet x la so tu nhien co 2 chu so va 12 < x <91

ban nao lam ho minh 3 bai tren voi ma ban nao nao lam ra dau tien minh se tich ngay va lun

A ) MUON THU LAI PHEP CONG , TA LAY TONG TRU DI MOT SO HANG , NEU DUOC KET QUA LA SO HANG CON LAI THI PHEP TINH LAM DUNG .  

B ) MUON THU LAI PHEP TRU , TA LAY SO BI TRU CONG VOI HIEU , NEU DUOC KET QUA LA SO TRU THI PHEP TINH LAM DUNG .

BAI TREN LA DUNG GHI D , SAI GHI S NHE

AI NHANH MINH TICK !            

muon tim mot so khi biet tong va ti so cua hai so do ta lam the nao

ai cho minh biet dau tien minh danh tick cho

mot phep cong co 2 so hang la 2 so chan lien tiep tong cac so  , so hang 1 tong so , so hang 2 la 276 . tim cac so do 

tong cua 2 so la 1991284 .so lon co chu so hang chuc la 5; hang don vi la 9 ;hang tram la 2 .neu xoa cac chu so do ta duoc so be .tim so be

tim tat cac so tu nhien co ba chu so thoan man cac tinh chat sau : co tong cac chu so bang 9 chu so hang chuc lom hon chu so hang don vi la 2 don vi va neu ta doi chu so hang tram cho hang don vi thi duoc so moi lon hon so ban dau la 198 don vi

Tim 3 so hang tiep theo cua day so:

a)1;3;4;7;...                       b)1;4;9;16;...

Bai nay minh da lam roi ,nhung minh muon chia se cho cac ban biet.

COI BAN NAO LAM DUOC BAI NAY!