1, tính nhanh các tổng sau
a,17+18+19+..99
b,23+25+...+49
c,46-45+44-43+..+2-1
d, 5+8+11+14+...+38+41
e, 49-51+53-55+57-59+61-63+65
TINH NHANH
a ) 199. 41
b) 101 .23
c ) 5 + 8 + 11 +... + 38 + 41
d ) 49 - 51 + 53 - 55 + 57 - 59 + 61 - 63 + 65
cac cau lam nhanh nha ghi ro rang nua va dung sai nha cam on nhieuuuuuuuuuuuuuuuuuu
tính nhanh
a, 2+5+11+...........+47+65
b, 1+6+11+16+......+46+51
c, 3+12+48+.......+3072+12288
d, 49-51+53-55+57-59+61-63+65
tính nhanh các tổng sau:
A=17+18+19+....+99
B=23+25+....+49
C=5+8+11+14+....+38+41
D=46-45+44-43+....+2-1
E=49-51+53-55+37+59+59-61-63+65
a) 5+8+11+...+41
b) 65-63+61-59+...+53-51+49
Tính nhanh
a) 5+8+11+14+...+38+41
b) 49-51+53-55+57-59+...+101-103+105-107
tính nhanh
49-51+53-55+57-59+61-63+65
Tính nhanh
49 - 51 + 53 - 55 + 57 - 59 + 61 - 63 + 65
Tính nhanh các tổng sau
a, 1+2+3+4+5+...+n
b, 1+3+5+7+...+(2n-1)
c, 2+4+6+8+...+2n
d, 2+5+11+...+47+65
e, 3+12+48+...+3072+12288
g, 2+5+7+12+...+81+131
h, 49-51+53-55+57-59+61-63+65