chỉ mình 2 câu này vs mik cảm ơn...
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chỉ mình 2 câu này vs mik cảm ơn tr
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TN
2
TN
2
KV
6 tháng 10 2023
cosx(1 + 1/cosx + tanx)(1 - 1/cosx + tanx)
= cosx[(1 + tanx)² - 1/cos²x]
= cosx(1 + tan²x + 2tanx - 1 - tan²x)
= 2tanxcosx
= 2sinxcosx/cosx
= 2sinx
Chọn D
6 tháng 10 2023
\(=cosx\left(1+\dfrac{1}{cosx}+\dfrac{sinx}{cosx}\right)\left(1-\dfrac{1}{cosx}+\dfrac{sinx}{cosx}\right)\)
\(=cosx\left(\dfrac{sinx+1+cosx}{cosx}\right)\left(\dfrac{cosx+sinx-1}{cosx}\right)\)
\(=\left(cosx+sinx\right)^2\)\(-1\)
\(=cos^2x+2cosxsinx+sin^2x-1\)
\(=cos^2x+sin^2x+2cosxsinx-1\)
\(=1+2cosxsinx-1\)
\(=2cosxsinx\)
Áp dụng đẳng thức góc nhân đôi cho sin
\(=2sinx\)
S
27 tháng 8 2021
1. If you are calm, you won't make a wrong decision.
2. These wonderful poems were written by a great poet.
3.Because of rained heavily, Jane didn't go fishing yesterday.
4.Vietnamese people use Khue Van pavilion as a symbol of Hanoi.
5. His idea is not the same as me.
6. Those modern paintings are not as expensive as these Dong Ho paintings.
7. What food do you like?
8.These machines are used by chefs to mix the ingredients.
9. It i've most seen such a boring movie.
10. There are not many eggs in the fridge.
11.They started living there 2 years ago.
12. I have never drunk cocktail before.
13.This exercise is not as difficult as the last one.
14. I find playing computer games boring.
15. The new building has the same height as the old one.
16. She didn't have enough eggs to make an omelette.
17. In spite of promising that wouldn't be late, he didn't arrive until 9 o'clock.
18. I didn't use to listen to Western music some years ago.
19. My mum used to be a chef in Cham restaurant, but now she is tired.
YT
2
YN
16 tháng 9 2021
\(5x\left(x-4y\right)-4y\)
Thay vào ta được:
\(5\left(\frac{-1}{5}\right)[\left(\frac{-1}{5}\right)-4\left(\frac{-1}{2}\right)]-4\left(\frac{-1}{2}\right)\)
\(=-[\left(\frac{-1}{5}\right)-2]-2\)
\(=\left(\frac{1}{5}-2\right)-2\)
\(=\frac{11}{5}-2\)
\(=\frac{1}{5}\)
16 tháng 9 2021
\(5x\left(x-4y\right)-4y=5x^2-20xy-4y\)
thay x= -1/5; y= -1/2 vào ta có:
\(5\left(-\frac{1}{5}\right)^2-20\left(-\frac{1}{5}\right)\left(-\frac{1}{2}\right)-4\left(-\frac{1}{2}\right)^2=\frac{5}{25}-\frac{20}{10}-\frac{4}{4}=\frac{1}{5}-2-1=\frac{1}{5}-\frac{15}{5}=-\frac{14}{5}\)
12 tháng 1 2022
My classes usually learn at half past seven.
TN
2
9 tháng 8 2021
1, What would he like to have for breakfast?
He would like to have a sandwich
2,Who would you like to go fishing with?
I would like to go fishing with my father
3,What would her children like to do in the summer?
They would like to go swimming
4,When would Mrs Tam like to go shopping?
She would like to go shopping at weekends
5,Where would Hung and Tung like to study
They would like to study in the library
DT
Đỗ Thanh Hải
CTVVIP
9 tháng 8 2021
1 What would he like for breakfast?
He'd like a sandwich
2 Who would you like to go fishing with?
I would like to go with my father
3 What would her children like to do in summer?
They would like to swim inpool
4 When would Mrs Tam like to go shopping?
She would like to go shopping on the weekends
5 Where would Tung and Hung like to study ?
THey would like to study in the school library
1.D 2.C