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Những câu hỏi liên quan
11 tháng 2 2022
1, What's the distance between Madrid and Barcelona?
2, Does your father not longer drive to work?
3, It is the first time I've ever seen such a boring movie
4, Despite the heavy rain, they still went hiking
5, It takes me half an hour to get to school
6, People will use biogas for fuel in houses and for transport
7, Are you interested in flying cars?
PT
1
Y
6 tháng 7 2023
\(VT=\sqrt{\dfrac{\sqrt{5}}{8\sqrt{5}+3\sqrt{35}}}.\left(3\sqrt{2}+\sqrt{14}\right)\)
\(=\sqrt{\dfrac{\sqrt{5}}{8\sqrt{5}+3\sqrt{5}.\sqrt{7}}}.\left(3\sqrt{2}+\sqrt{2}.\sqrt{7}\right)\)
\(=\sqrt{\dfrac{\sqrt{5}}{\sqrt{5}\left(8+3\sqrt{7}\right)}}.\left[\sqrt{2}\left(3+\sqrt{7}\right)\right]\)
\(=\sqrt{\dfrac{1}{8+3\sqrt{7}}}.\left[\sqrt{2}\left(3+\sqrt{7}\right)\right]\)
\(=\dfrac{\sqrt{2}\left(3+\sqrt{7}\right)}{\sqrt{8+3\sqrt{7}}}\)
\(=\dfrac{\sqrt{2}.\sqrt{2}\left(3+\sqrt{7}\right)}{\sqrt{2}.\sqrt{8+3\sqrt{7}}}\) (Nhân \(\sqrt{2}\) cả tử và mẫu)
\(=\dfrac{2\left(3+\sqrt{7}\right)}{\sqrt{16+6\sqrt{7}}}\)
\(=\dfrac{2\left(3+\sqrt{7}\right)}{\sqrt{\left(3+\sqrt{7}\right)^2}}\)
\(=\dfrac{2\left(3+\sqrt{7}\right)}{\left|3+\sqrt{7}\right|}\)
\(=\dfrac{2\left(3+\sqrt{7}\right)}{3+\sqrt{7}}\)
\(=2=VP\left(dpcm\right)\)
T
1
NV
Nguyễn Việt Lâm
Giáo viên
10 tháng 9 2021
Do \(\dfrac{a}{b}=\dfrac{c}{d}\Rightarrow\dfrac{b}{a}=\dfrac{d}{c}\)
\(\Rightarrow1-\dfrac{b}{a}=1-\dfrac{d}{c}\Rightarrow\dfrac{a-b}{a}=\dfrac{c-d}{c}\) (đpcm)
LT
3
N
6 tháng 11 2021
Bài 1:
\(54\left(\dfrac{km}{h}\right)=15\left(\dfrac{m}{s}\right);9\left(\dfrac{m}{s}\right)=32,4\left(\dfrac{km}{h}\right)\)
Baì 2:
\(t'=s':v'=5:\left(5.3,6\right)=\dfrac{5}{18}h\)
\(\Rightarrow v_{tb}=\dfrac{s'+s''}{t'+t''}=\dfrac{5+3,8}{\dfrac{5}{18}+\left(\dfrac{15}{60}\right)}\simeq16,67\left(\dfrac{km}{h}\right)\)
7 tháng 11 2021
Câu 2:
\(\Leftrightarrow\left(x+2\right)\left(10x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=-\dfrac{3}{10}\end{matrix}\right.\)
2 tháng 10 2021
\(A1+2=A2\)
\(\overline{A}\) =\(\dfrac{A1\cdot54+\cdot\left(A1+2\right)\cdot46}{100}\)=79.92
\(\Leftrightarrow\)A1=79\(\Rightarrow\)A2=81
3) \(x+\frac{3}{16}=-\frac{5}{24}\)\(\Rightarrow x=-\frac{5}{24}-\frac{3}{16}\)
\(\Rightarrow x=\frac{-1}{48}\Rightarrow\text{ ta chọn B}\)
4) \(\left(7-\frac{2}{3}-\frac{1}{4}\right)-\left(\frac{4}{3}-\frac{10}{4}\right)-\left(\frac{5}{4}-\frac{1}{3}\right)\)
\(=7-\frac{2}{3}-\frac{1}{4}-\frac{4}{3}+\frac{10}{4}-\frac{5}{4}+\frac{1}{3}\)
\(=7+\left(-\frac{2}{3}+\frac{1}{3}-\frac{4}{3}\right)+\left(-\frac{1}{4}+\frac{10}{4}-\frac{5}{4}\right)\)
\(=7-\frac{5}{3}+1=6\frac{1}{3}\)=> ta chọn B