A= 6+16+30+48+...+19600+19998
B=2+5+9+14+...+4949+5049
Tính nhanh
A=6+16+30+48+...+19600+19998
B=2+5+9+14+...+4949+5049
C=1.2.3+2.3.4+3.4.5+...+98.99.100
A=6+16+30+48+...+19600+19998
2A = 1.3+2.4+3.5+...+99.101
B=2+5+9+14+...+4949+5049
2A = 1.4+2.5+3.6+...+99.102
C=1.2.3+2.3.4+3.4.5+...+98.99.100
4A = 1.2.3.4+2.3.4(5-1)+3.4.5.(6-2)+...+98.99.100.(101-97)
4A = 1.2.3.4+2.3.4.5-1.2.3.4+3.4.5.6-2.3.4.5+...+98.99.100.101-97.98.99.100
4A = 98.99.100.101
A=6+16+30+48+...+19600+19998
A : 2 = 3 + 8 + 15 + 24 + . . . + 9800 + 9999
A : 2 = 1.3 + 2.4 + 3.5 + 4.6 + . . . + 98.100 + 99.101
A : 2 = 1.[1+2] + 2.[1+3] + 3.[1+4] + 4.[1+5] + . . . + 98.[1+99] + 99.[1+100]
A : 2 = 1 + 1.2 + 2 + 2.3 + 3 + 3.4 + 4 + 4.5 + . . . + 98 + 98.99 + 99 + 99.100
A : 2 = 1 + 2 + 3 + 4 + . . . + 199 + 1.2 + 2.3 + 3.4 + 4.5 + . . . + 98.99 + 99.100
A : 2 = 4950 + 333300
A = 676500
F=1.3+2.4+3.5+...+2013.2015
J=6+16+30+...+19600+19998
K=2+5+9+14+...+4949+5049
Tính Tổng Của Từng Kết Qủa
tính tổng sau
a,6+16+30+48+...............+19 600+19 998
b, 2+5+9+14+........+4949+5049
Tính :
A = 4 + 12 + 24 + 40 + .......+ 19404 + 19800
B = 1 + 3 + 6 + 10 + .......... + 4851 +4950
C = 6 + 16 + 30 + 48 + ........... + 19600 + 19998
D = 2 + 5 + 9 + 14 + ............+ 4949 + 5044
rút gọn giá trị của các biểu thức sau
J=6+16+30+48+......+19600+19998
k=2+5+9+14+....+4949+5049
L=22+42+62+........+982+1002
M=13+23+33+....+993+1003
N=1+52+53+....+5100
O=1+31+32+......+3100
J=6 + 16 + 30 + 48 +...+ 19600 + 19998
Chia cả 2 vế cho 2 ta được
B/2 = 3 + 8 + 15 + 24 + ......... + 98000+ 9999
B/2= 1x3+2x4+3x5+4x6+…….+98x100+99x101
B/2= 100/6[(100-1)x(2x100+1)] = 328350
-> B =328350x2=656700
K=2 + 5 + 9 + 14 + ....+ 4949 + 5049
Nhân cả 2 vế với 2 ta được
2xD=1x4+ 2x5+ 3x6+ 4x7+……..+98x101+99x102
2xD = 1(2+2)+2(3+2)+3(4+2)+...+99(100+2)
2xD = 1x2+1x2+2x3+2x2+3x4+3x2+...+99x100+99x2
2xD= (1x2+2x3+3x4+...+99x100)+2(1+2+3+...+99)
2xD = 333300 + 9900 = 343200
-> D= 343200 :2 =171600
Tính: A=2+5+9+14+...+4949+5049
1 . A = 1 x 4 + 2 x 5 + 3x 6 + .... + 99 x 102
2 . A = 1 + 3 + 6 + 10 + ... + 4851 + 4950
3 . A = 6 + 16 + 30 + 48 + ... + 19600 + 19998
4 . A = 2 + 5 + 9 + 14 + ... + 4949 + 5049
5 . A = 22 + 42 + 62 + ... + 982 + 1002
6 . A = 1 x3 + 3 x 5 + 5 x 7 + .... + 97 x 99 + 99 x 101
7 . A = 12 + 32 + 52 + ... + 972 + 992
8 . A = 13 + 23 + 33 + ... + 993 + 1003
Giair hộ mik nhé !
Tính : A = 2 + 5 + 9 Ơ 14 +...+ 4949 + 5049
A=2+5+9+14+....+4949+5049