a) Calculate:1 + 3 + 5 + ...... + 57 = .....
b) Calculate:3 - 1 + 5 - 3 + 7 - 5 + ... + 99 - 97 =....
A = 1-2+3-4+5-6+.....+97-98+99-100+101
B = 1+2-3-4+5+6-7-8+......+98-99-100+101
1)Tính:
a)100-99+98-97+.............+4-3+2-1
b)99-97+95-93+...............+7-5+3-1
2/1*3+2/3*5+2/5*7+...+2/99*101 = ?
tính
a, 100 - 99 +98 - 97 + .......................... + 4-3+2-1
b, 99 - 97 + 95 - 93 + ............................ + 7-5+ 3-1
Bài 8:
a)100-99+98-97+..+4-3+2-1=?
b)99-97+95-93+...+7-5+3-1=?
tính nhanh :
1 / 1*3 + 1 / 3*5 + 1 / 5*7 + 1 / 7*9 +..... + 1 / 99 * 101
giúp mình cả cách giải nha ?
1+3+5+7+9+...+99=?
1+3+5+7+...+97+99