Gợi ý nhé lấy P nhân 3 rùi lấy 3P-P
\(\text{P=1.2+2.3+3.4+...+98.99}\)
\(3P=3.\left(1.2+2.3+3.4+...+98.99\right)\)
\(3P=1.2.3+2.3.3+3.4.3+...+98.99.3\)
\(3P=1.2.3+2.3.\left(4-1\right)+3.4.\left(5-2\right)+...+98.99.\left(100-97\right)\)
\(3P=1.2.3+2.3.4-2.3.1+3.4.5-3.4.2+...+98.99.100-98.99.97\)
\(3P=98.99.100\)
\(P=98.99.100:3\)
\(P=323400\)
Hok tốt!
Tính các biểu thức sau:
C=1.2+2.3+3.4+...+98.99
D=(1.99+2.99+3.99+...99.99)-(1.2+2.3+3.4+...98.99
tính 1.2+2.3+3.4+...+98.99
1.2+2.3+3.4+4.5+...+98.99
1.2+2.3+3.4+...+98.99+99.100
1.2+2.3+3.4+4.5+...+98.99
1.2+2.3+3.4+4.5+...+98.99+99.100=?
B=1.2+2.3+3.4+...+98.99+99.100
( 1.2 + 2.3 + 3.4 +.............+ 98.99) tính tổng
A=1.2+2.3+3.4+...+98.99.Tính A
