làm hộ mình bài 2 ạ
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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
T
1
NN
Nguyễn Ngọc Anh Minh
CTVHS
VIP
31 tháng 10 2023
2/
a/
\(\dfrac{4n+2}{n+1}=\dfrac{4n+4-2}{n+1}=\dfrac{4\left(n+1\right)-2}{n+1}=4-\dfrac{2}{n+1}\)
\(\Rightarrow4n+2⋮n+1\) Khi \(n+1=\left\{-2;-1;1;2\right\}\Rightarrow n=\left\{-3;-2;0;1\right\}\)
b/
\(\Rightarrow a+2=\dfrac{8}{b-1}\left(b\ne1\right)\) (1)
a nguyên => a+2 nguyên \(\Rightarrow8⋮\left(b-1\right)\)
\(\Rightarrow b-1=\left\{-8;-4;-2;-1;1;2;4;8\right\}\)
\(\Rightarrow b=\left\{-7;-3;-1;0;2;3;5;9\right\}\) Thay các giá trị của b vào (1) để tìm a
3/
Gọi số tiền mẹ cho Chi là A \(\Rightarrow100000\le A\le200000\)
Nếu bớt số tiền mẹ cho Chi đi 5000 đồng thì
\(A-5000⋮15000;A-5000⋮8000\)
\(\Rightarrow A-5000=UC\left(8000;15000\right)\) Và \(95000\le A-5000\le195000\)
\(\Rightarrow A-5000=120000\Rightarrow A=125000\)
NH
Nguyễn Hải Phong
VIP
18 tháng 12 2023
<=>55 - 3x = 25
<=>-3x = 25 - 55
<=>-3x = -30
<=>x=10
18 tháng 12 2023
55 - 3x = (-5)2
55 - 3x = 25
3x = 55 - 25
3x = 30
x = 30 : 3
x = 10
Vậy x = 10
DN
TimTim nha
2
DT
Đỗ Thanh Hải
CTVVIP
9 tháng 7 2021
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
9 tháng 7 2021
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
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