A=1(2+1)+2(3+1)+3(4+1)+...99(100+1)
A=1.2+1.2.3+2+3.4+3+...+99.100+99
A=(1.2+2.3+3.4+...+99.100)+(1+2+3+...+99)
A=333300+4950=338250
tính hợp lí :
B=\(\frac{1\cdot4}{2\cdot3}+\frac{2\cdot5}{3\cdot4}+\frac{3\cdot6}{4\cdot5}+.....+\frac{98\cdot101}{99\cdot100}\)
Q=( \(1+\frac{1}{1\cdot3}\)) * ( \(1+\frac{1}{2\cdot4}\)) * ( \(1+\frac{1}{3\cdot5}\)) * ... * (\(1+\frac{1}{99\cdot101}\))
Tính bằng cách thuận thiện:
\(\left(1+\dfrac{1}{1\cdot3}\right)\left(1+\dfrac{1}{2\cdot4}\right)...\left(1+\dfrac{1}{99\cdot101}\right)\)
Hãy tính tổng: \(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+...+\frac{2}{99\cdot101}\)
Tính
\(1\cdot2\cdot3+2\cdot3\cdot4+3\cdot4\cdot5+...+2015\cdot2016\cdot2017\)
\(B=\left(\frac{1}{1\cdot3}\right)\left(\frac{1}{2\cdot4}\right)............\left(\frac{1}{99\cdot101}\right)\)
tính B
đúng tick
Tính nhanh
B=\(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+\frac{1}{3\cdot4\cdot5}+...+\frac{1}{98\cdot99\cdot100}\)
Tính \(M=\frac{1}{1\cdot2\cdot3}=\frac{1}{2\cdot3\cdot4}=\frac{1}{3\cdot4\cdot5}+...+\frac{1}{37\cdot38\cdot39}\)Giúp mình giải nhé mai đi học rồi. Cảm ơn nhiều =]]z
Tìm x biết: \(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+\frac{1}{3\cdot4\cdot5}+...+\frac{1}{8\cdot9\cdot10}\cdot x=\frac{22}{45}\)Trình bày cách tính