\(\Rightarrow2S=1+\frac{1}{2}+...+\frac{1}{2^{19}}\)

\(\Rightarrow2S-S=\left(1+\frac{1}{2}+...+\frac{1}{2^{19}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{20}}\right)\)

\(\Rightarrow S=1-\frac{1}{2^{20}}< 1\)

Ta có: S = \(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{20}}\)

    1/2S = \(\frac{1}{2}.\left(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{20}}\right)\)

   1/2S = \(\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{21}}\)

   1/2S - S = \(\left(\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{21}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{20}}\right)\)

  -1/2S = \(\frac{1}{2^{21}}-\frac{1}{2}\)

       S = \(\left(\frac{1}{2^{21}}-\frac{1}{2}\right):\left(-\frac{1}{2}\right)\)

       S =\(\frac{1}{2^{21}}:\left(-\frac{1}{2}\right)-\frac{1}{2}:\left(-\frac{1}{2}\right)\)

      S = \(-\frac{1}{2^{20}}+1=1-\frac{1}{2^{20}}< 1\)

98642579763280+74765647666365497535898549743=7.4765648e+28

tk mk đi

=7476564767..............

rồi k cho mình đi

17 / 33

a.\(\frac{17}{16}\)

b.\(\frac{16}{17}\)

c.\(\frac{16}{33}\)

d.\(\frac{17}{33}\)

hãy chọn đáp án đúng nhé

\(2A=4\left(m+p\right)+2mp-2m^2-2p^2=\left(-m^2+4m-4\right)+\left(-p^2+4p-4\right)+\left(-m^2+2mp-p^2\right)+8\)

\(=-\left(m-2\right)^2-\left(p-2\right)^2-\left(m-p\right)^2+8\le8\)

=> \(A\le4\)

"=" <=> m=p=2

\(A=\frac{1}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+...+\frac{2}{2011.2013}\right)\)

\(A=\frac{1}{2}.\left(1-\frac{1}{2013}\right)\)

\(A=\frac{1}{2}.\frac{2012}{2013}\)

\(A=\frac{1006}{2013}\)

\(A=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2011.2013}\)

\(A=\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2011}-\frac{1}{2013}\right)\)

\(A=\frac{1}{2}.\left(1-\frac{1}{2013}\right)\)

\(A=\frac{1}{2}.\frac{2012}{2013}\)

\(A=\frac{1006}{2013}\)

4387 + 4398

= 8785

Câu trả lời :

1 cái hố nhỏ hơn

Hok tốt nha ! ^.^

4387 + 4398 = 8785

     Hai ng đào trong 2h thì đc 1 cái hố 

=> Một ng đào đc 1h chưa đc cái hố nào :D

Áp dụng bđt quen thuộc \(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\ge\frac{9}{a+b+c}\left(a;b;c>0\right)\)  được

\(\frac{1}{x}+\frac{2}{y}=\frac{1}{x}+\frac{1}{y}+\frac{1}{y}\ge\frac{9}{x+2y}=\frac{9}{3}=3\)

Dấu "=" tại x = y = 1

mình nè , kết bạn nhé

BN

KO

NÊN

ĐĂNG

CÂU

HỎI

LINH

TINH

LÊN

DIỄN

ĐÀN

\(25\%.x+x=-1,25\)

\(\frac{1}{4}x+x.1=\frac{-5}{4}\)

\(\left(\frac{1}{4}+1\right)x=\frac{-5}{4}\)

\(\frac{5}{4}x=\frac{-5}{4}\)

\(x=\frac{-5}{4}:\frac{5}{4}\)

\(x=-1\)