Đặt A=1.2.3+2.3.4+3.4.5+4.5.6+...+98.99.100
4A=(1.2.3+2.3.4+3.4.5+4.5.6+...+98.99.100)4
4A=1.2.3(4-0)+2.3.4(5-1)+3.4.5(6-2)+4.5.6(7-3)+...+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+4.5.6.7-3.4.5.6+...+98.99.100.101-97.98.99.100
4A=1.2.3.4-1.2.3.4+2.3.4.5-2.3.4.5+3.4.5.6-3.4.5.6+...+97.98.99.100-97.98.99.100+98.99.100.101
4A=98.99.100.101
=>A=98.99.100.101/4
=> A=24497550
1/2 + 2/3 + 3/4 + 4/5 + 5/6 + 6/7 + 7/8 + 8/9 + ........+ 95/96 + 96/97 + 97/98 + 98/99 + 99/100 = ?
Tính tổng
A=\(1^3+2^3+3^3+...+100^3\)
B=\(2^3+4^3+...+98^3\)
C=\(1^3+3^3+5^3+...+99^3\)
D=\(1^3-2^3+3^3-4^3+...+99^3-100^3\)
Tính A= 2^3+ 4^3+ 6^3+ ...+98^3+ 100^3
B= 1^3+ 3^3+ 5^3+ ...+97^3+ 99^3
C= 1^3+ 2^3- 3^3+ 4^3- 5^3+ 6^3- ...+98^3- 99^3+ 100^3
a)A=1-2+3-4+...+99-100
b)B=1-2-3+4+5-6-7+...+97-98-99+100
c)C=2100-299s-998-...-22-2-1
giup mik vs a
Tính A= 2^3+ 4^3+ 6^3+ ...+98^3+ 100^3
B= 1^3+ 3^3+ 5^3+ ...+97^3+ 99^3
C= 1^3+ 2^3- 3^3+ 4^3- 5^3+ 6^3- ...+98^3- 99^3+ 100^3
Tính nhanh :B=1*4/2*3+2*5/3*4+...+98*101/99*100
Tính
P= 1/1*2*3 + 1/2*3*4 + 1/3*4*5 +........+1/98*99*100
1+2+3+4+5...98+99+100
A= 1/2+2/3+3/4+4/5+............+98/99+99/100
A bằng bao nhiêu
