Tính nhanh
B=3^2/1.3+3^2/3.5+3^2/5.7+...+3^2/95.97+3^2/97.99
g=1.3^2+3.5^2+5.7^2+...+97.99^2
Câu 2 tính nhanh
a) A=2005+2006+2007+2008+2009+15
C=3/1.3-3/3.5-3/5.7-..........-3/97.99
Tính :
A=1.32+3.52+5.72+...+97.992
Cho A =2/1.3+2/3.5+2/5.7+2/7.9+....2/97.99
tính nhanh: D=1.3+3.5+5.7+.......+97.99
B= \(\dfrac{2}{1.3}\) + \(\dfrac{2}{3.5}\) +\(\dfrac{2}{5.7}\) +...+ \(\dfrac{2}{97.99}\) + \(\dfrac{2}{99.101}\)
Tính B=1.32+3.52+5.72+....+97.992
Tính giá trị biêut hức;B=2/1.3-4/3.5+6/5.7-8/7.9+...-96/95.97+98/97.99