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15 tháng 5 2021
Câu 2:
a) Ta có: \(-7x+21< 0\)
\(\Leftrightarrow-7x< -21\)
hay x>3
Vậy: S={x|x>3}
15 tháng 5 2021
Câu 2:
b) Ta có: x<y
nên -x>-y
\(\Leftrightarrow-x+2021>-y+2021\)
mà \(-y+2021>-y+2020\)
nên -x+2021>-y+2020
hay 2021-x>2020-y
24 tháng 5 2022
C1
A. baseball - football - volleyball - basketball - ice hockey
B. judo - gymnastics
C. skiing - ice-skating - horse-riding
18 tháng 2 2021
1) Vì x=25 thỏa mãn ĐKXĐ nên Thay x=25 vào biểu thức \(A=\dfrac{\sqrt{x}-2}{x+1}\), ta được:
\(A=\dfrac{\sqrt{25}-2}{25+1}=\dfrac{5-2}{25+1}=\dfrac{3}{26}\)
Vậy: Khi x=25 thì \(A=\dfrac{3}{26}\)
2) Ta có: \(B=\dfrac{\sqrt{x}-3}{\sqrt{x}+1}+\dfrac{2x+8\sqrt{x}-6}{x-\sqrt{x}-2}\)
\(=\dfrac{\left(\sqrt{x}-3\right)\left(\sqrt{x}-2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}+\dfrac{2x+8\sqrt{x}-6}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{x-5\sqrt{x}+6+2x+8\sqrt{x}-6}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{3x+3\sqrt{x}}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{3\sqrt{x}\left(\sqrt{x}+1\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{3\sqrt{x}}{\sqrt{x}-2}\)
NH
0
30 tháng 3 2021
Câu IV:
1) Xét tứ giác BFEC có
\(\widehat{BFC}=\widehat{BEC}\left(=90^0\right)\)
\(\widehat{BFC}\) và \(\widehat{BEC}\) là hai góc cùng nhìn cạnh BC
Do đó: BFEC là tứ giác nội tiếp(Dấu hiệu nhận biết tứ giác nội tiếp)
hay B,F,E,C cùng nằm trên 1 đường tròn(đpcm)
1 She failed to do everything she was supposed to do
2 There is no likelihood that anyone will apply for this post
3 He succeeded in finishing the English test in time
4 There is no likelihood that the situation will improve in the near future
5 There is a chance that you will get what you want there
6 Don't check your answers before answering all the questions
7 I won't give an opinion before thinking this through
8 The judge will decide after hearing all the evidence
9 I won't be able to have a holiday until I save enough money
10 There is little likelihood that my sister will win the first prize in the singing contest
11 He made no reference of his new job when I last spoke to him
1 She failed to do everything she was supposed to do
2 There is no likelihood that anyone will apply for this post
3 He succeeded in finishing the English test in time
4 There is no likelihood that the situation will improve in the near future
5 There is a chance that you will get what you want there
6 Don't check your answers before answering all the questions
7 I won't give an opinion before thinking this through
8 The judge will decide after hearing all the evidence
9 I won't be able to have a holiday until I save enough money
10 There is little likelihood that my sister will win the first prize in the singing contest
11 He made no reference of his new job when I last spoke to him