Cho S = \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+...+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}\)

\(\Rightarrow S=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^9}\)

\(\Rightarrow2S=2.\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^9}\right)\)

\(\Rightarrow2S=1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^8}\)

\(\Rightarrow2S-S=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^8}-\left(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)

\(\Rightarrow S=1-\frac{1}{2^9}\) \(=\frac{511}{512}\)

Chúc bn hc tốt!

=\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+....+\frac{1}{512}\)

\(=\)CÂU HỎI TƯƠNG TỰ NHA

= BN BIẾN ĐỔI TUNWHF MẪU THÀNH LŨY THỪA 2 ĐI 

MÌNH KO CÓ HỜI GIAN

0,785

1/5

1/2 x 1/2 x 3/,14 = 0,785

2/5 : 2 = 1/5

\(\frac{1}{2}x\frac{1}{2}x3,14=0,785\)

\(\frac{2}{5}:2\)\(=\frac{1}{5}\)

\(\left(3\frac{1}{2}+5\frac{2}{3}\right)\times\frac{8}{19}-\left(2\frac{1}{2}+4\frac{2}{3}\right)\times\frac{8}{19}\)

\(=\frac{8}{19}\times\left[\left(3\frac{1}{2}+5\frac{2}{3}\right)-\left(2\frac{1}{2}+4\frac{2}{3}\right)\right]\)

\(=\frac{8}{19}\times\left(3\frac{1}{2}+5\frac{2}{3}-2\frac{1}{2}-4\frac{2}{3}\right)\)

\(=\frac{8}{19}\times\left[\left(3\frac{1}{2}-2\frac{1}{2}\right)+\left(5\frac{2}{3}-4\frac{2}{3}\right)\right]\)

\(=\frac{8}{19}\times\left(1+1\right)\)

\(=\frac{8}{19}\times2=\frac{16}{19}\)

1 phần 4 của 8 kg chứ

lôn ngược lại là bt bằng bao nhiêu

1 phần 4 của 8 kg

đổi ngược là 1/4 của 8kg

=2kg

\(\sqrt{12}+\sqrt{27}-\sqrt{108}-\dfrac{1}{4}\sqrt{192}\)

\(=\sqrt{2^2.3}+\sqrt{3^2.3}-\sqrt{6^2.3}-\dfrac{1}{4}\sqrt{8^2.3}\)

\(=2\sqrt{3}+3\sqrt{3}-6\sqrt{3}-\dfrac{1}{4}.8\sqrt{3}=-3\sqrt{3}\)

A = 19\(\dfrac{1}{4}\) + \(\dfrac{1}{2\dfrac{1}{3}}\) + 5,75 - \(\dfrac{1}{6}\) + 74

A = \(\dfrac{77}{4}\) + \(\dfrac{1}{\dfrac{7}{3}}\) + 5,75 - \(\dfrac{1}{6}\) + 74

A = \(\dfrac{77}{4}\) + \(\dfrac{3}{7}\) + \(\dfrac{23}{4}\) - \(\dfrac{1}{6}\) + 74

A = \(\dfrac{3234}{168}\) + \(\dfrac{72}{168}\) + \(\dfrac{966}{168}\) - \(\dfrac{28}{168}\) + \(\dfrac{12432}{168}\)

A =  \(\dfrac{16676}{168}\)

A = \(\dfrac{4169}{42}\)