giúp mik câu 7 đến câu 15 lm được hết thì càng tốt ạ.
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
21 tháng 9 2023
Bài 1: - \(\dfrac{5}{7}\) x \(\dfrac{31}{33}\) + \(\dfrac{-5}{7}\) x \(\dfrac{2}{33}\) + 2\(\dfrac{5}{7}\)
= - \(\dfrac{5}{7}\) \(\times\) ( \(\dfrac{31}{33}\) + \(\dfrac{2}{33}\)) + 2 + \(\dfrac{5}{7}\)
= - \(\dfrac{5}{7}\) + 2 + \(\dfrac{5}{7}\)
= 2
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
21 tháng 9 2023
2, \(\dfrac{3}{14}\): \(\dfrac{1}{28}\) - \(\dfrac{13}{21}\): \(\dfrac{1}{28}\) + \(\dfrac{29}{42}\): \(\dfrac{1}{28}\) - 8
= (\(\dfrac{3}{14}\) - \(\dfrac{13}{21}\) + \(\dfrac{29}{42}\)) : \(\dfrac{1}{28}\) - 8
= \(\dfrac{2}{7}\) x 28 - 8
= 8 - 8
= 0
C
1
8 tháng 10 2023
a: \(=\dfrac{-\dfrac{1}{2}\left[cos\left(a+b+a-b\right)-cos\left(a+b-a+b\right)\right]}{cos^2b-cos^2a}\)
\(=\dfrac{-\dfrac{1}{2}\cdot\left[cos2a-cos2b\right]}{\dfrac{1-cos2b}{2}-\dfrac{1-cos2a}{2}}\)
\(=\dfrac{-\dfrac{1}{2}\cdot\left(cos2a-cos2b\right)}{\dfrac{1-cos2b-1+cos2a}{2}}=\dfrac{-\dfrac{1}{2}\cdot\left(cos2a-cos2b\right)}{\dfrac{1}{2}\cdot\left(cos2a-cos2b\right)}=-1\)
c: \(T=\dfrac{sina+sinb\cdot\left(cosa\cdot cosb-sina\cdot sinb\right)}{cosa-sinb\cdot\left(sina\cdot cosb+sinb\cdot cosa\right)}-tan\left(a+b\right)\)
\(=\dfrac{sina+sinb\cdot cosa\cdot cosb-sin^2b\cdot sina}{cosa-sinb\cdot sina\cdot cosb-sin^2b\cdot cosa}-tan\left(a+b\right)\)
\(=\dfrac{sina\left(1-sin^2b\right)+sinb\cdot cosa\cdot cosb}{cosa\left(1-sin^2b\right)-sinb\cdot sina\cdot cosb}\)-tan(a+b)
\(=\dfrac{sina\cdot cos^2b+sinb\cdot cosa\cdot cosb}{cosa\cdot cos^2b-sinb\cdot sina\cdot cosb}-tan\left(a+b\right)\)
\(=\dfrac{sina\cdot cosb+sinb\cdot cosa}{cosa\cdot cosb-sina\cdot sinb}-tan\left(a+b\right)\)
\(=\dfrac{sin\left(a+b\right)}{cos\left(a+b\right)}-tan\left(a+b\right)=0\)
NL
6
NV
Nguyễn Việt Lâm
Giáo viên
4 tháng 3 2022
4.
\(\lim\limits_{x\rightarrow8}f\left(x\right)=\lim\limits_{x\rightarrow8}\dfrac{\sqrt[3]{x}-2}{x-8}=\lim\limits_{x\rightarrow8}\dfrac{x-8}{\left(x-8\right)\left(\sqrt[3]{x^2}+2\sqrt[3]{x}+4\right)}=\lim\limits_{x\rightarrow8}\dfrac{1}{\sqrt[3]{x^2}+2\sqrt[3]{x}+4}\)
\(=\dfrac{1}{4+4+4}=\dfrac{1}{12}\)
\(f\left(8\right)=3.8-20=4\)
\(\Rightarrow\lim\limits_{x\rightarrow8}f\left(x\right)\ne f\left(8\right)\)
\(\Rightarrow\) Hàm gián đoạn tại \(x=8\)
5.
\(\lim\limits_{x\rightarrow0^+}f\left(x\right)=\lim\limits_{x\rightarrow0^+}\dfrac{\sqrt[]{1+2x}-1+1-\sqrt[3]{1+3x}}{x}=\lim\limits_{x\rightarrow0^+}\dfrac{\dfrac{2x}{\sqrt[]{1+2x}+1}-\dfrac{3x}{1+\sqrt[3]{1+3x}+\sqrt[3]{\left(1+3x\right)^2}}}{x}\)
\(=\lim\limits_{x\rightarrow0^+}\left(\dfrac{2}{\sqrt[]{1+2x}+1}-\dfrac{3}{1+\sqrt[3]{1+3x}+\sqrt[3]{\left(1+3x\right)^2}}\right)=\dfrac{2}{1+1}-\dfrac{3}{1+1+1}=0\)
\(f\left(0\right)=\lim\limits_{x\rightarrow0^-}f\left(x\right)=\lim\limits_{x\rightarrow0^-}\left(3x^2-2x\right)=0\)
\(\Rightarrow\lim\limits_{x\rightarrow0^+}f\left(x\right)=\lim\limits_{x\rightarrow0^-}f\left(x\right)=f\left(0\right)\)
\(\Rightarrow\) Hàm liên tục tại \(x=0\)
NV
Nguyễn Việt Lâm
Giáo viên
4 tháng 3 2022
6.
\(\lim\limits_{x\rightarrow0^+}f\left(x\right)=\lim\limits_{x\rightarrow0^+}\dfrac{\sqrt[]{4x+1}-\sqrt[3]{6x+1}}{x^2}\)
\(=\lim\limits_{x\rightarrow0^+}\dfrac{\sqrt[]{4x+1}-\left(2x+1\right)+\left(2x+1-\sqrt[3]{6x+1}\right)}{x^2}\)
\(=\lim\limits_{x\rightarrow0^+}\dfrac{\dfrac{-x^2}{\sqrt[]{4x+1}+2x+1}+\dfrac{x^2\left(8x+12\right)}{\left(2x+1\right)^2+\left(2x+1\right)\sqrt[3]{6x+1}+\sqrt[3]{\left(6x+1\right)^2}}}{x^2}\)
\(=\lim\limits_{x\rightarrow0^+}\left(\dfrac{-1}{\sqrt[]{4x+1}+2x+1}+\dfrac{8x+12}{\left(2x+1\right)^2+\left(2x+1\right)\sqrt[3]{6x+1}+\sqrt[3]{\left(6x+1\right)^2}}\right)\)
\(=\dfrac{-1}{1+1}+\dfrac{12}{1+1+1}=\dfrac{7}{2}\)
\(f\left(0\right)=\lim\limits_{x\rightarrow0^-}f\left(x\right)=\lim\limits_{x\rightarrow0^-}\left(2-3x\right)=2\)
\(\Rightarrow\lim\limits_{x\rightarrow0^+}f\left(x\right)\ne\lim\limits_{x\rightarrow0^-}f\left(x\right)\)
\(\Rightarrow\) Hàm gián đoạn tại \(x=0\)
25 tháng 1 2022
a) \(\left(-23\right)+230+23=0+230=230.\)
b) \(124.\left(-54\right)+24.54=54.\left(-124+24\right)=54.\left(-100\right)=-5400.\)
c) \(-927+1421+930+\left(-1421\right).\)
\(=-927+930=3.\)
25 tháng 1 2022
a) (-23) + 230 + 23 =230
b) 124 . (-54) + 24 . 54 =− 5400.
c) -927 + 1421 + 930 + (-1421) =3.
d) (-351) + (-74) + 51 + (-126) + 149=-351
DT
Đỗ Thanh Hải
CTVVIP
3 tháng 8 2021
10. ……………. festival do you choose? - I choose Elephant Race Festival.
A. What B. How C. Which D. When
11. ……………. often is Burning Festival held? - It's held every year.
A. Which B. When C. What D. How
12. ……………. does the teacher say La Tomatina sounds unusual? - Because people throw tomatoes at each other for one hour at the festival.
A. What B. When C. Why D. How
13. He ___________ books for poor children for years.
A. has collected B. collects C. is collecting D. collected
14. Next Saturday at this time, we _____ on the beach in Mexico.
A. will relax B. will be relaxing C. has relaxed D. relax
15. Anne and Joe _____ by sea tomorrow
A. travel B. will travel C. travels D. travelled
16. I_____ in Jakarta, but now I live in New York. [use to + V-inf]
A. used to living B. used to living C. used to live D. am used to live
17. Jane_____ for the telephone company, but now she has a job at the post office.
A. used to working B. used to worked C. is used to work D. used to work
18. …………. he spent much money on the film, it wasn't a big success.
A. Even B. But C. Although D. Despite
19. We didn't find it funny………..it was a comedy.
A. in spite of B. despite C. although D. but
20. I went to the cinema with my friends yesterday ………… feeling very tired.
A. although B. in spite C. despite D. but
21. Let's go to the Victor Cinema. I'm sure you'll find the film…………
A. excites B. excite C. excited D. exciting
22. I was ……… to learn that the director of that gripping film has won the first prize.
A. interest B. interests C. interested D. interesting
23. The film was boring, ____ we went home.
A. so B. when C. but D. if
24. Nam was absent from class yesterday ____ he felt sick.
A. so B. because C. although D. but
25. These books aren’t yours, ____________?
A.are these B. aren’t these C. are they D. aren’t they
26. No one died in the accident, ______________?
A.did they B. didn’t they C. did he D. didn’t he
27. Tom knows Alice, _____________?
A.doesn’t he B. is he C. does he D. isn’t he
28. Peter never comes to class late, ________________?
A. doesn’t he B. doesn’t Peter C. does he D. does Peter
29. ……… computer is a laptop, but ……… is a desktop.
A. Hers - you B. Her - your C. My - yours D. Mine - yours
30. We gave them ……… ID number, and they gave us ……….
A. ours - theirs B. our - theirs C. our -their D. ours - their
KY
3 tháng 8 2021
Mn giúp mik ak câu nào mn bt thì lm còn lm hết đc thì càng tốt nhé TKS
10. ……………. festival do you choose? - I choose Elephant Race Festival.
A. What B. How C. Which D. When
11. ……………. often is Burning Festival held? - It's held every year.
A. Which B. When C. What D. How
12. ……………. does the teacher say La Tomatina sounds unusual? - Because people throw tomatoes at each other for one hour at the festival.
A. What B. When C. Why D. How
13. He ___________ books for poor children for years.
A. has collected B. collects C. is collecting D. collected
14. Next Saturday at this time, we _____ on the beach in Mexico.
A. will relax B. will be relaxing C. has relaxed D. relax
15. Anne and Joe _____ by sea tomorrow
A. travel B. will travel C. travels D. travelled
16. I_____ in Jakarta, but now I live in New York. [use to + V-inf]
A. used to living B. used to living C. used to live D. am used to live
17. Jane_____ for the telephone company, but now she has a job at the post office.
A. used to working B. used to worked C. is used to work D. used to work
18. …………. he spent much money on the film, it wasn't a big success.
A. Even B. But C. Although D. Despite
19. We didn't find it funny………..it was a comedy.
A. in spite of B. despite C. although D. but
20. I went to the cinema with my friends yesterday ………… feeling very tired.
A. although B. in spite C. despite D. but
21. Let's go to the Victor Cinema. I'm sure you'll find the film…………
A. excites B. excite C. excited D. exciting
22. I was ……… to learn that the director of that gripping film has won the first prize.
A. interest B. interests C. interested D. interesting
23. The film was boring, ____ we went home.
A. so B. when C. but D. if
24. Nam was absent from class yesterday ____ he felt sick.
A. so B. because C. although D. but
25. These books aren’t yours, ____________?
A.are these B. aren’t these C. are they D. aren’t they
26. No one died in the accident, ______________?
A.did they B. didn’t they C. did he D. didn’t he
27. Tom knows Alice, _____________?
A.doesn’t he B. is he C. does he D. isn’t he
28. Peter never comes to class late, ________________?
A. doesn’t he B. doesn’t Peter C. does he D. does Peter
29. ……… computer is a laptop, but ……… is a desktop.
A. Hers - you B. Her - your C. My - yours D. Mine - yours
30. We gave them ……… ID number, and they gave us ……….
A. ours - theirs B. our - theirs C. our -their D. ours - their
MH
29 tháng 12 2020
Câu 1:
Thành phần chủ yếu của tế bào thực vật:
– Vách tế bào (chỉ có ở tế bào thực vật): quy định và duy trì hình dạng tế bào.
– Màng sinh chất: bao bọc bên ngoài chất tế bào.
– Chất tế bào: dạng keo lỏng, bên trong chứa các bào quan (lục lạp, không bào, ribôxôm, …).
– Nhân: điều khiển hoạt động sống của tế bào.
AH
Akai Haruma
Giáo viên
9 tháng 9 2023
Với số to như 25764 bạn muốn kiểm tra có chia hết cho 8 không thì có thể lấy 3 chữ số cuối cùng. Nếu 3 chữ số cuối cùng tạo thành số chia hết cho 8 thì cả số đó chia hết cho 8 còn không thì không chia hết.
Trong TH này 764 không chia hết cho 8 nên 25764 cũng không chia hết cho 8.
\(7,x^4+x^3+x^2-1=x^3\left(x+1\right)+\left(x-1\right)\left(x+1\right)=\left(x^3+x-1\right)\left(x+1\right)\)
\(8,x^2y^2+1-x^2-y^2=\left(x^2y^2-y^2\right)-\left(x^2-1\right)\\ =y^2\left(x^2-1\right)-\left(x^2-1\right)=\left(x-1\right)\left(x+1\right)\left(y-1\right)\left(y+1\right)\)
\(10,x^4-x^2+2x-1=x^4-\left(x-1\right)^2=\left(x^2-x+1\right)\left(x^2+x-1\right)\\ 11,3a-3b+a^2-2ab+b^2=3\left(a-b\right)+\left(a-b\right)^2=\left(3+a-b\right)\left(a-b\right)\\ 12,a^2+2ab+b^2-2a-2b+1=\left(a+b\right)^2-2\left(a+b\right)+1=\left(a+b-1\right)^2\\ 13,a^2-b^2-4a+4b=\left(a-b\right)\left(a+b\right)-4\left(a-b\right)=\left(a+b-4\right)\left(a-b\right)\\ 14,a^3-b^3-3a+3b=\left(a-b\right)\left(a^2+ab+b^2\right)-3\left(a-b\right)=\left(a-b\right)\left(a^2+ab+b^2-3\right)\\ 15,x^3+3x^2-3x-1=\left(x-1\right)\left(x^2+x+1\right)+3x\left(x-1\right)=\left(x-1\right)\left(x^2+4x+1\right)\)
1)
=0,25y.(64x3+z3)
2)
=x2(x2-4x+4)
=x2(x-2)2
5)
=x2(x+1)-4(x+1)
=(x2-4)(x+1)
=(x-2)(x+2)(x+1)
6)
=x2(x-1)-(x-1)
=(x2-1)(x-1)
=(x-1)(x+1)(x-1)
=(x-1)2(x+1)