giải hộ mình nha
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\(\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+...+\frac{1}{11\times12}\)
\(=\frac{4-3}{3\times4}+\frac{5-4}{4\times5}+\frac{6-5}{5\times6}+...+\frac{12-11}{11\times12}\)
\(=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{11}-\frac{1}{12}\)
\(=\frac{1}{3}-\frac{1}{12}\)
\(=\frac{1}{4}\)
4x5x6/3x10x8=120/240=120:120/240:120=1/2 nha
~HT~
k cho mình nha
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1) Ta có: |x+3| \(\ge\)0; |2x+y-4| \(\ge\)0
\(\Rightarrow\) |x + 3| + |2x + y - 4| \(\ge\) 0
Dấu = xảy ra khi x+3=0 và 2x+y-4 = 0 \(\Rightarrow\)x=-3; y=10
1) |x + 3| + |2x + y - 4| = 0
\(\Leftrightarrow\hept{\begin{cases}x+3=0\\2x+y-4=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=-3\\-6+y-4=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=-3\\y=10\end{cases}}\)
giải giúp mình bài nay bằng máy tính casio hộ mình nha(nhớ giải chi tiết hộ mình)
tính: \(1023456^3\)
Bài 3: Số học sinh giỏi của lớp 4A là: 1 - 1/5 - 2/7 = 18/35 số học sinh
\(\dfrac{x}{a}=\dfrac{y}{b}=\dfrac{z}{c}=\dfrac{x+y+z}{a+b+c}=\dfrac{x+y+z}{1}=x+y+z\)
\(\Rightarrow\dfrac{x^2}{a^2}=\dfrac{y^2}{b^2}=\dfrac{z^2}{c^2}=\left(x+y+z\right)^2\) (1)
\(\dfrac{x}{a}=\dfrac{y}{b}=\dfrac{z}{c}\Rightarrow\dfrac{x^2}{a^2}=\dfrac{y^2}{b^2}=\dfrac{z^2}{c^2}=\dfrac{x^2+y^2+z^2}{a^2+b^2+c^2}=\dfrac{x^2+y^2+z^2}{1}=x^2+y^2+z^2\) (2)
(1);(2) \(\Rightarrow\left(x+y+z\right)^2=x^2+y^2+z^2\)
Bạn tham khảo nha:
* \(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{4}=\dfrac{a}{2}=\dfrac{2b}{6}=\dfrac{c}{4}=\dfrac{a+2b+c}{2+6+4}=\dfrac{a+2b+c}{12}\) (1)
* \(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{4}=\dfrac{a+b-c}{2+3-4}=\dfrac{a+b-c}{2+3-4}=\dfrac{a+b-c}{1}\) (2)
(1)(2)=> \(\dfrac{a+2b+c}{12}=\dfrac{a+b-c}{1}=\dfrac{a+2b-c}{a+b-c}=\dfrac{12}{1}=12\)
=> H = 12.
Kết quả: Chọn C.
Chúc bạn học tốt :D
c) \(x-\dfrac{10}{3}=\dfrac{7}{15}\cdot\dfrac{3}{5}\)
\(x-\dfrac{10}{3}=\dfrac{7}{25}\)
\(x=\dfrac{7}{25}+\dfrac{10}{3}\)
\(x=\dfrac{271}{75}\)
d) \(x+\dfrac{3}{22}=\dfrac{27}{121}\div\dfrac{9}{11}\)
\(x+\dfrac{3}{22}=\dfrac{3}{11}\)
\(x=\dfrac{3}{11}-\dfrac{3}{22}\)
\(x\) \(=\dfrac{3}{22}\)
e) \(\dfrac{8}{23}\div\dfrac{24}{46}-x=\dfrac{1}{3}\)
\(\dfrac{2}{3}-x=\dfrac{1}{3}\)
\(x=\dfrac{2}{3}-\dfrac{1}{3}\)
\(x=\dfrac{1}{3}\)
f) \(1-x=\dfrac{49}{65}\cdot\dfrac{5}{7}\)
\(1-x=\dfrac{7}{13}\)
\(x=1-\dfrac{7}{13}\)
\(x=\dfrac{6}{13}\)
11 , How are store gas done ?
12 , Are red shoes worn ?
13 , Where is my book put ?
14 , Vietnamese isn't spoken
15 , This book isn't bought
16 , Fish isn't eaten
11. How is gas stored?
12. Are red shoes worn by them? (Hoặc bỏ by them cũng được)
13. Where is my book put?
14. Vietnamese isn't spoken by her. ( Hoặc bỏ by her cũng được)
15. This book isn't bought by me.
16. Fish isn't eaten by us.
Đây bạn nha