\(A=\left(\frac{1}{2^2}-1\right).\left(\frac{1}{3^2}-1\right).\left(\frac{1}{4^2}-1\right)...\left(\frac{1}{2013^2}-1\right).\left(\frac{1}{2014^2}-1\right)\)
\(A=\frac{1}{2}+\left(\frac{1}{2}\right)^2\left(\frac{1}{2}\right)^3+...+\left(\frac{1}{2}\right)^{2013}+\left(\frac{1}{2}\right)^{2014}\)
Chứng minh A< 1
Cho A= \(\left(\frac{1}{2^2}-1\right)\left(\frac{1}{3^2}-1\right)\left(\frac{1}{4^2}-1\right)...\left(\frac{1}{2013^2}-1\right)\left(\frac{1}{2014^2}-1\right)\) và B=\(\frac{-1}{2}\). Hãy so sánh A và B
A = \(\left(1-\frac{1}{2^2}\right)\left(1-\frac{1}{3^2}\right)\left(1-\frac{1}{4^2}\right)...\left(1-\frac{1}{2017^2}\right).\)
B = \(\frac{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{6}}{\frac{2015}{1}+\frac{2014}{2}+\frac{2013}{3}+...+\frac{1}{2015}}\)
So sánh : A=\(\left(\frac{1}{2^2}\right).\left(\frac{1}{3^2}\right).\left(\frac{1}{4^2}\right)....\left(\frac{1}{2013^2}\right).\left(\frac{1}{2014^2}\right)\)
B = \(-\frac{1}{2}\)
\(y=\left(\frac{1}{2^2}-1\right)\left(\frac{1}{3^2}-1\right)\left(\frac{1}{4^2}-1\right)....\left(\frac{1}{2013^2}-1\right)\left(\frac{1}{2014^2}-1\right)\)
x= -1/2
hãy so sánh x và y
Cho A = \(\left(\frac{1}{2^2}-1\right)\left(\frac{1}{3^2}-1\right)\left(\frac{1}{4^2}-1\right).....\left(\frac{1}{2013^2}-1\right)\left(\frac{1}{2014^2}-1\right)\) và B = \(\frac{-1}{2}\). Hãy so sánh A và B
Tính tổng: \(A=\frac{1}{2.\left(1+2\right)}+\frac{1}{3.\left(1+2+3\right)}+\frac{1}{4.\left(1+2+3+4\right)}+...+\frac{1}{2013.\left(1+2+3+...+2013\right)}\)
tìm x y z
a , | x - 1 | + |3 - x | = 2x - 1
b , \(\left|x^2+x+1\right|=x^2+2\)2
c , \(\left(x+1\right)^{30}+\left|y+2\right|+\left|x^2+z\right|=0\)
d , \(\left(\frac{1}{2}+\frac{1}{3}+.....+\frac{1}{2014}\right).x=\frac{2013}{1}+\frac{2012}{2}+.....+\frac{1}{2013}\)
e , \(\left|\left(x+2\right).\left(x^2-15\right)\right|=x+2\)