Ta có nhận xét sau
Với n là số nguyên dương thì
\(\frac{1}{n\left(n+1\right)}=\frac{1}{n}-\frac{1}{\left(n+1\right)}\)
Áp dụng vào , ta có
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}=1-\frac{1}{4}=\frac{3}{4}\)
1/2 + 1/6 + 1/12
=(1/1 x 2) + (1/2 x 3) + (1/3 x 4)
=1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4
=1/1 - 1/4
=4/4 - 1/4
=3/4
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}=\frac{6}{12}+\frac{2}{12}+\frac{1}{12}\)
\(=\frac{8}{12}+\frac{1}{12}\)
\(=\frac{9}{12}=\frac{3}{4}\)
\(\frac{1}{2}\) + \(\frac{1}{6}\) + \(\frac{1}{12}\)
= \(\frac{6}{12}\) + \(\frac{1}{12}\)
= \(\frac{9}{12}\) = \(\frac{3}{4}\)
1/2 + 1/6+ 1/12 =6/12 + 2/ 12 + 1 /12 =9 / 12 = 3 /4
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}\)
\(=\frac{6}{12}+\frac{2}{12}+\frac{1}{12}\)
\(=\frac{9}{12}\)
\(=\frac{3}{4}\)
1/2 + 1/6 + 1/12
= 6/12+2/12+ 1/12
= 8/12+1/12
= 9/12
1/2 + 1/6 + 1/12
= 6/12 + 2/12 + 1/12
= 9/12 = 3/4
Chúc bạn học tốt!
1/2 + 1/6 + 1/12
= 6/11 + 2/11 + 1/12
= 9/12
= 3/4
ờ chắc bằng 1/38 hi hi mình ko biết