Tìm x
\(\frac{-3}{29}+\frac{-7}{29}\le\frac{x}{29}\le\frac{-3}{29}-\frac{5}{29}\)
Tìm \(n\in Z\)để \(\frac{n^2+n-5}{n+2}\)là số nguyên
Tính \(S=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+......+\frac{1}{2^{99}}+\frac{1}{2^{100}}\)
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I. Choose the word whose underlined part is pronounced differently from that of the other words in each group
1. A. mind B. climb C. exciting D. destination
2. A. sugar B. sorry C. seaside D. summer
3. A. busy B. why C. history D. family
4. A. page B. villaage C. luggage D. heritage
5. A. what B. which C. where D. who
II. Give the correct form of the words
1. Lan (be) _was________ very tired when she (cacth) __caught__________ a bad cold two days ago.
2. Everybody (wait) _is waiting__________ for the president inthe hall now.
3. You should (go) ___go________ to bed early.
4. I hope you (feel) ____will feel________ better soon.
5. She needs (eat) _____to eat_______ a lot vegetables and fruits.
6. He (not come) ___didn't come_________ to the meeting last week.
7. My father never (take) __takes__________ medicine.
8. There (be) _____was________ nobody there when I (arrive) __arrived__________ yesterday.
I
1 .D
2. C
3. B
4. A
5. D
II.
1. was - caught
2. is waiting
3. go
4. will feel
5. to eat
6. didn't come
7. takes
8. was - arrived
Bài làm
a) \(58.\left(3\frac{1}{29}-2\frac{1}{28}\right):\frac{1}{3}\)
\(=58.\left(\frac{88}{29}-\frac{57}{28}\right).3\)
\(=58.\left(\frac{2464}{812}-\frac{1653}{812}\right).3\)
\(=58.\frac{811}{812}.3\)
\(=\frac{811}{14}.3\)
\(=\frac{2433}{3}\)
b) \(17.\left(\frac{5}{17}-\frac{1}{34}+\frac{1}{2}\right):\frac{3}{4}\)
\(=17.\left(\frac{10}{34}-\frac{1}{34}+\frac{17}{34}\right).\frac{4}{3}\)
\(=17.\frac{26}{34}.\frac{4}{3}\)
\(=\frac{26}{2}.\frac{4}{3}\)
\(=\frac{52}{3}\)
# Học tốt #
100 m đường chiếm:
1 - 4/9 = 5/9
Họ được giao hoàn thành đường dài:
100 : 5/9 =180 (m)
Đáp số: 180 m
vì \(\widehat{xOy}\)và \(\widehat{yOz}\)kề bù
\(\Rightarrow\widehat{xOy}+\widehat{yOz}=180^O\)
mà \(\widehat{xOy}=118^o\)
\(\Rightarrow118^o+\widehat{yOz}=180^o\)
\(\Rightarrow\widehat{yOz}=62^o\)
Vây.........
O x y z
Ta có: góc xOy + góc yOz = 1800
=> góc yOz = 1800 - góc xOy
=> góc yOz = 1800 - 1180
=> góc yOz = 620
Vậy góc yOz = 620
Vì số HS lớp 6A chiếm \(\frac{1}{3}\) số HS cả khối => lớp 6A có: \(120\cdot\frac{1}{3}=40\) ( HS )
Đổi: \(45\%=\frac{45}{100}=\frac{9}{20}\)
Số HS lớp 6B và 6C là: 120 - 40 = 80 ( HS )
Vì số HS lớp 6B chiếm \(45\%=\frac{9}{20}\) tổng số HS lớp 6B và 6C => Lớp 6B có: \(80\cdot\frac{9}{20}=36\) ( HS )
=> Số HS lớp 6C là: \(120-40-36=44\) ( HS )
Số học sinh lớp 6A là: 120 x 1/3= 40
Số học sinh lớp 6B là: 120 x 45%=120 x 9/20=54
Số học sinh lớp 6C là: 120 - (40+54)=26
\(\frac{3}{2\cdot4}+\frac{3}{4\cdot6}+\frac{3}{6\cdot8}+...+\frac{3}{96\cdot98}\)
\(=\frac{3}{2}\cdot\left(\frac{2}{2\cdot4}+\frac{2}{4\cdot6}+\frac{2}{6\cdot8}+...+\frac{2}{96\cdot98}\right)\)
\(=\frac{3}{2}\cdot\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{96}-\frac{1}{98}\right)\)
\(=\frac{3}{2}\cdot\left(\frac{1}{2}-\frac{1}{98}\right)=\frac{3}{2}\cdot\left(\frac{48}{98}-\frac{1}{98}\right)\)
\(=\frac{3}{2}\cdot\frac{47}{98}=\frac{141}{196}\)
a, \(\frac{7}{30}=\frac{7\cdot4}{30\cdot4}=\frac{28}{120}\)
\(\frac{13}{60}=\frac{12\cdot2}{60\cdot2}=\frac{24}{120}\)
\(-\frac{9}{40}=\frac{-9\cdot3}{40\cdot3}=\frac{-27}{120}\)
- Câu b đề k rõ... câu c tương tự câu a nha bạn :)
\(1,-\frac{3}{29}+\frac{-7}{29}\le\frac{x}{29}\le-\frac{3}{29}-\frac{5}{29}\)
\(\Rightarrow-\frac{10}{29}\le\frac{x}{29}\le-\frac{8}{29}\Rightarrow-10\le x\le-8\)
\(\Rightarrow x=\left\{-8;-9;-10\right\}\)
\(S=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\)
\(\Rightarrow2S=1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}\)
\(S=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\)
\(\Rightarrow2S-S=S=1-\frac{1}{2^{100}}\)