Tổng trên = 1-2^2/2^2 . 1-3^2/3^2 . ..... . 1-100^2/100^2
= -(2^2-1/2^2 . 3^2-1/3^2 . ...... . 100^2-1/100^2 )
= -(1.3/2^2 . 2.4/3^2 . ..... . 99.101/100)
= -(1.2.3. .... .99 . 3.4.5. ... .101 / 2.3.4 . ... . 100 . 2.3.4 . ..... . 100)
= -(1.2.3. ... . 99/2.3.4. .... .100) . (3.4.5. .... .101/2.3.4 . .... . 100)
= -1/100 . 101/2 = -101/200
Tk mk nha
So sanh
\(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{90}+\frac{1}{100}.\)va 100
cac ban giai chi tiet giup mk voi
Bai 1 : Thuc hien cac phep tinh ( tinh nhanh neu co the ) :
a) \(2\frac{1}{3}-\frac{1}{3}\)\(:\)\(\left[15\%+\left(-\frac{2}{3}+0,4.5\right)\right]\)
GIUP MK VOI NHA
MK DAG CAN GAP
AI LAM NHANH VA DUNG THI MK SE TICK CHO NHA ^ _ <
Chứng minh rằng: \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{100^2}< 1\)1
ai nhanh nhất mk tk nha ,kb vs mk
bai 1 :thuc hien phep tinh
a)\(\frac{-5}{2}:\left(\frac{3}{4}-\frac{1}{2}\right)\) b) \(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\) c)\(\left(\frac{-5}{24}+0,75+\frac{7}{12}\right):\left(-2\frac{1}{4}\right)^2\)
AI LAM NHANH VA DUNG THI MK SE TICK CHO NHA
MK DAG CAN GAP !!!!!!! CAC BAN LAM NHANH LEN NHA
Cau 1 : Tinh hop ly
a) (326-43) + (174-57)
b) (351-875) - (125-149)
c) -418-{-218-[-118-(-318)+2012)]}
d) (-2)+7+(-12)+17+...+(-52)+57
e) (-30)+(-29)+...+49+50
Mk se tick cho ai tra loi cho mk dau tien nko ghi cach lm nx nhe thank you cac bn
tim x la so nguyen
1. \(\frac{12}{x}=\frac{x}{3}\)
2. \(\frac{x}{2}+\frac{x}{3}=\frac{1}{4}\)
giai giup mk nha cac bn
tinh hop li :
\(\frac{\left(\frac{1}{5}-\frac{2}{7}\right)\cdot\frac{3}{4}-\frac{3}{4}\cdot\left(\frac{1}{3}-\frac{2}{7}\right)}{\frac{1}{5}\cdot\frac{2}{7}-\frac{1}{3}\cdot\left(\frac{2}{7}+\frac{3}{9}\right)+\frac{3}{9}+\frac{1}{5}}\)
cham la nhan nha cac ban
ai nhanh mk tick cho
Tinh cac tong sau
\(H=\frac{1}{7}+\frac{1}{7^2}+\frac{1}{7^3}+...+\frac{1}{7^{100}}\)
\(I=\frac{4}{5}+\frac{4}{5^2}+\frac{4}{5^3}+...+\frac{4}{5^{200}}\)
Cho
\(A=\frac{1}{^{1^2}}+\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+....+\frac{1}{50^2}\)
Chứng minh A < 2
Nhanh giúp mk nha , ai nhanh nhất chính xác nhất mk sẽ tick
