Tính và so sánh: - 1 2 2 5
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Bài 1:
a) \(\dfrac{-17}{36}\) và \(\dfrac{23}{-48}\)
\(\dfrac{-17}{36}=\dfrac{-17.4}{36.4}=\dfrac{-68}{144}\)
\(\dfrac{23}{-48}=\dfrac{-23}{48}=\dfrac{-23.3}{144.3}=\dfrac{-69}{144}\)
Vì \(\dfrac{-68}{144}>\dfrac{-69}{144}\) nên \(\dfrac{-17}{36}>\dfrac{23}{-48}\)
b) \(\dfrac{-1}{3}\) và \(\dfrac{2}{5}\)
Vì \(\dfrac{-1}{3}\) là số âm mà \(\dfrac{2}{5}\) là số dương nên \(\dfrac{-1}{3}< \dfrac{2}{5}\)
c) \(\dfrac{2}{7}\) và \(\dfrac{5}{4}\)
Vì \(\dfrac{2}{7}< 1\) mà \(\dfrac{5}{4}>1\) nên \(\dfrac{2}{7}< \dfrac{5}{4}\)
d) \(\dfrac{267}{-268}\) và \(\dfrac{-1347}{1343}\)
\(\dfrac{267}{-268}=\dfrac{-267}{268}=\dfrac{-267.449}{268.449}=\dfrac{-119883}{120332}\)
\(\dfrac{-1347}{1343}=\dfrac{-1347.89}{1343.89}=\dfrac{-119883}{119527}\)
Vì \(\dfrac{-119883}{120332}>\dfrac{-119883}{119527}\) nên \(\dfrac{267}{-268}>\dfrac{-1347}{1343}\)
Bài 2:
\(\dfrac{5}{2}-\left(1\dfrac{3}{7}-0,4\right)=\dfrac{5}{2}-\dfrac{10}{7}-\dfrac{2}{5}=\dfrac{47}{70}\)
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\(\left[\frac{1}{3}+(\frac{-1}{2})\right]+\frac{3}{5}=\frac{1}{3}-\frac{1}{2}+\frac{3}{5}=\frac{-1}{6}+\frac{3}{5}=\frac{-5+18}{30}=\frac{13}{30}\)
\(\frac{1}{3}+(\frac{-1}{2}+\frac{3}{5})=\frac{1}{3}+\frac{-5+6}{10}=\frac{1}{3}+\frac{1}{10}=\frac{10+3}{30}=\frac{13}{30}\)
Mà 13 = 13 => \(\frac{13}{30}=\frac{13}{30}\)hay \(\left[\frac{1}{3}+(\frac{-1}{2})\right]+\frac{3}{5}=\frac{1}{3}+(\frac{-1}{2}+\frac{3}{5})\)
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Bài 1:
a: Sửa đề: 1/3^200
1/2^300=(1/8)^100
1/3^200=(1/9)^100
mà 1/8>1/9
nên 1/2^300>1/3^200
b: 1/5^199>1/5^200=1/25^100
1/3^300=1/27^100
mà 25^100<27^100
nên 1/5^199>1/3^300
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1. bigger - the biggest
2. hotter - the hottest
3. sweeter - the sweetest
4. few - the fewest
5. less - thee least
6. more comfortable - the most comfortable
7. more important - the most important
8. expensive - the most expensive
9. better - the best
10. father/further - the farthest/the furthest
ADJ/ADV | So sánh hơn | So sánh nhất |
1. Big | bigger | biggest |
2. Hot | hotter | hottest |
3. Sweet | sweeter | sweetest |
4. Few | fewer | fewest |
5. Little | more little | the most little |
6. Comfortable | more comfortable | the most comfortable |
7. Important | more important | the most.. |
8. Expensive | more expensive | the most.. |
9. Good | better | the best |
10. Far | more far | the most far |
![](https://rs.olm.vn/images/avt/0.png?1311)
1.
- Lan is taller than My
- My house is bigger than your house
- Things in this shop are more expensive than things in the supermarket
- This park is more beautiful than that park
- Ann is slimmer than Laura
2.
So sánh ngang bằng
- Công thức: as + adj + as
- Ví dụ: Lan is 16. I’m 16, too. Lan is as young as I.(Lan trẻ như tôi)
Study well !
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Bài 6:
a: \(15=\sqrt{225}>\sqrt{200}\)
b: \(27=9\sqrt{9}>9\sqrt{5}\)
c: \(-24=-\sqrt{576}< -\sqrt{540}=-6\sqrt{15}\)