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DN
1
5 tháng 10 2021
\(W=\dfrac{1}{2}\left(\sqrt{\left(2+\sqrt{2}\right)^2}+\sqrt{\left(2-\sqrt{2}\right)^2}\right)\\ W=\dfrac{1}{2}\left(2+\sqrt{2}+2-\sqrt{2}\right)=\dfrac{1}{2}\cdot4=2\\ Y=\dfrac{1}{2}\left(\sqrt{\left(4+\sqrt{3}\right)^2}+\sqrt{\left(4-\sqrt{3}\right)^2}\right)\\ Y=\dfrac{1}{2}\left(4+\sqrt{3}+4-\sqrt{3}\right)=\dfrac{1}{2}\cdot8=4\)
AT
15 tháng 7 2021
m) \(\sqrt{82+12\sqrt{42}}=\sqrt{\left(3\sqrt{6}\right)^2+2.3\sqrt{6}.2\sqrt{7}+\left(2\sqrt{7}\right)^2}\)
\(=\sqrt{\left(3\sqrt{6}+2\sqrt{7}\right)^2}=3\sqrt{6}+2\sqrt{7}\)
o) \(\sqrt{14-6\sqrt{5}}+\sqrt{14-6\sqrt{5}}\)
\(=\sqrt{3^2-2.3.\sqrt{5}+\left(\sqrt{5}\right)^2}+\sqrt{3^2+2.3.\sqrt{5}+\left(\sqrt{5}\right)^2}\)
\(=\sqrt{\left(3-\sqrt{5}\right)^2}+\sqrt{\left(3+\sqrt{5}\right)^2}=3-\sqrt{5}+3+\sqrt{5}=6\)
v) \(\sqrt{18+4\sqrt{6}+8\sqrt{3}+4\sqrt{2}}\)
\(=\sqrt{2^2+\left(\sqrt{2}\right)^2+\left(2\sqrt{3}\right)^2+2.2\sqrt{3}.\sqrt{2}+2.2\sqrt{3}.2+2.2.\sqrt{2}}\)
\(=\sqrt{\left(2+\sqrt{2}+2\sqrt{3}\right)^2}=2+\sqrt{2}+2\sqrt{3}\)
w) \(\sqrt{49-5\sqrt{96}}+\sqrt{49+5\sqrt{96}}=\sqrt{\dfrac{98-10\sqrt{96}}{2}}+\sqrt{\dfrac{98+10\sqrt{96}}{2}}\)
\(=\sqrt{\dfrac{\left(5\sqrt{2}\right)^2-2.5\sqrt{2}.4\sqrt{3}+\left(4\sqrt{3}\right)^2}{2}}+\sqrt{\dfrac{\left(5\sqrt{2}\right)^2+2.5\sqrt{2}.4\sqrt{3}+\left(4\sqrt{3}\right)^2}{2}}\)
\(=\sqrt{\dfrac{\left(5\sqrt{2}-4\sqrt{3}\right)^2}{2}}+\sqrt{\dfrac{\left(5\sqrt{2}+4\sqrt{3}\right)^2}{2}}\)
\(=\dfrac{5\sqrt{2}-4\sqrt{3}}{\sqrt{2}}+\dfrac{5\sqrt{2}+4\sqrt{3}}{\sqrt{2}}=\dfrac{10\sqrt{2}}{\sqrt{2}}=10\)
TH
0
NT
10
17 tháng 4 2021
dạ ko ạ,em hỏi mấy anh chị cho nhanh thôi ạ
KY
9 tháng 9 2021
1. The jar __________ peanut butter. A. contain B. is containing C. contains D. has contained 2. Ho Chi Minh city ________ in the south of Viet Nam. A. is lying B. lie C. lies D. lay 3. One of my shoes __________ off as I was climbing out of the pit. A. fell B. was falling C. has fallen D. had fallen 4. She ______ down the hill when I ___________ her. A. ran/ was seeing B. had run/ saw C. was running/ saw D. ran/ saw 5. All kinds of wonderful toys _______ at that shop. A. sold B. were selling C. are being sold D. have sold 6. They _______ when the thief _______ their house. A. are sleeping/ enters B. were sleeping/entered C. slept/ was entering D. were sleeping/ was entering
TB
0
ý là cân bằng hả?, mạng có mà:v?
\(Fe_2O_3+3CO\underrightarrow{t^o}2Fe+3CO_2\)
chuyển sang box hóa rồi hả chị