\(\frac{4}{3.6}+\frac{4}{6.9}+...+\frac{4}{12.15}\)
\(=\frac{4\left(\frac{3}{3.6}+\frac{3}{6.9}+...+\frac{3}{12.15}\right)}{3}\)
\(=\frac{4\left(\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+...+\frac{1}{12}-\frac{1}{15}\right)}{3}\)
\(=\frac{4\left(\frac{1}{3}-\frac{1}{15}\right)}{3}\)
\(=\frac{\frac{16}{15}}{3}=\frac{48}{15}\)
\(\frac{4}{3.6}\)+ \(\frac{4}{6.9}\)+ \(\frac{4}{9.12}\)+\(\frac{4}{12.15}\)
= 4(\(\frac{1}{3.6}\)+\(\frac{1}{6.9}\)+\(\frac{1}{9.12}\)+\(\frac{1}{12.15}\))
=\(\frac{4}{3}\)( \(\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+\frac{1}{9}-\frac{1}{12}+\frac{1}{12}-\frac{1}{15}\) )
=\(\frac{4}{3}\)(\(\frac{1}{3}-\frac{1}{15}\))
=\(\frac{4}{3}\).\(\frac{4}{15}\)
=\(\frac{16}{45}\)
mk làm đúng chưa
\(\left(\frac{-1}{3.6}-\frac{1}{6.9}-\frac{1}{9.12}-\frac{1}{12.15}:\left|x\right|=\frac{-8}{15}\right)\)
tính tổng
4/1.3 + 6 / 3.6 + 8/6.10+14/10.17+ 12/17.23
bạn nào trả lời nhanh mình tick cho nha
Tính tổng:
N=2/3.6+2/6.9+2/9.12+....+2/2019.2022
Tính A=1/3.6+1/6.9+.....+1/113.116
Tính
a,B=2.4+4.6+6.8+...+98.100
b,B=3+3.6+6.9+...+96.99
tính nhanh tổng sau:(4/3.7)+(4/7.11)+...+(4/23.27)
1) Tính nhanh:
\(10\cdot\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}\)
tính tổng
1.4+2.5+3.6+4 .7+...+n.[n+3]
