Lời giải:
$A=1.2+2.3+3.4+...+50.51$
$3A=1.2(3-0)+2.3(4-1)+3.4(5-2)+...+50.51(52-49)$
$=(1.2.3+2.3.4+3.4.5+...+50.51.52)-(0.1.2+1.2.3+2.3.4+....+49.50.51)$
$=50.51.52$
$\Rightarrow A=50.51.52:3=44200$
Tính:
S = 1.2 + 2.3 + 3.4 +...+ 50.51
Thực hiện phép tính:
1.2+2.3+3.4+...+49.50+50.51
tính tổng 1.2+2.3+3.4+...+50.51
ai ghi ca bai ra thi minh moi tick
A=1.2-2.3+3.4-4.5+...+49.50-50.51
TÍNH NHANH
A= 1/1.2+1/2.3+1/3.2+...+1/50.51
B= 3/2.3+3/3.8+3/8.11+...+3/47.50
A=1/1.2+1/2.3+1/3.4+....+1/50.51
B=2/3.5+2/5.7+2/7.9+....+2/51.53
C=6/4.7+6/7.10+6/10.13+....+6/73.76
GIÚP MIK VỚI CẢM ƠN MN.
D = 5/2.3 - 7/3.4 + 9/4.5 - 11/5.6 + ... + 101/50.51 + 102/51/52
Tính nhanh
C=1.2+2.3+3.4+...+2014.2015
K=1.2+2.3+3.4+..+(n-1).n
Tính
a) S= 1.2+2.3+3.4+...+32.33
b) S= 1.2+2.3+3.4+...+49.50
