Tính D=\(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\)
E=\(\frac{3}{7.10}+\frac{3}{10.13}+\frac{3}{13.16}+...+\frac{3}{254.257}\)
F=\(\frac{5}{7.10}+\frac{5}{10.13}+\frac{5}{13.16}+...+\frac{5}{254.257}\)
M=\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{98.99.100}\)
các bn tính cho mik nha nhớ ghi cả lời giải
Bài 1 : tính hợp lý :
a) A = \(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+\frac{1}{13.16}+\frac{1}{16.19}\)
b) B = \(\frac{1}{32}+\frac{1}{96}+\frac{1}{192}+\frac{1}{320}+\frac{1}{480}\)
Bài 1 : tính hợp lý :
a) A = \(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+\frac{1}{13.16}+\frac{1}{16.19}\)
b) B = \(\frac{1}{32}+\frac{1}{96}+\frac{1}{192}+\frac{1}{320}+\frac{1}{480}\)
So sánh A và B biết
a,A=6\(\left(x+\frac{1}{3}\right)^2\)
,B=-8-(3,75-x)2
b,A=\(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+\frac{3}{13.16}\)
B=\(\left(\frac{1}{2}\right)^4\)
Tính giá trị biểu thức:
\(A=\left(\frac{1}{4.9}+\frac{1}{9.14}+\frac{1}{14.19}+...+\frac{1}{44.49}\right).\frac{1-3-5-7-...-49}{89}\)
\(B=\frac{5}{1.2}+\frac{13}{2.3}+\frac{25}{3.4}+\frac{41}{4.5}+...+\frac{181}{9.10}\)
tính \(B=\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}.+....+\frac{1}{301.304}\)
a) \(\frac{1}{1.2}\) + \(\frac{1}{2.3}\)+ \(\frac{1}{3.4}\)+ \(\frac{1}{4.5}\)+ ..... +\(\frac{1}{99.100}\)
b) \(\frac{1}{1.2.3}\)+ \(\frac{1}{2.3.4}\)+ \(\frac{1}{3.4.5}\)+ .......+ \(\frac{1}{98.99.100}\)
Tính nhanh, biết
a) \(A=\frac{1}{3.4}-\frac{1}{4.5}-\frac{1}{5.6}-\frac{1}{6.7}-\frac{1}{7.8}-\frac{1}{8.9}-\frac{1}{9.10}\)
b) \(B=1+\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{49}-\frac{1}{50}\)
tính:A=\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{98.99.100}\)
CMR:
\(\frac{1}{1.2.3}+\frac{1}{2.3.\text{4}}+\frac{1}{3.\text{4}.5}+...+\frac{1}{98.99.100}=\frac{\text{4}9\text{4}9}{19800}\)
