Lemon Tea
Nguyễn Ngọc Lộc
Vài giây trước

+1 còn tùy vào từng loại cần tìm nếu đơn giản là đa thức bậc 2 thì sử dụng máy tính hoặc cứ tìm thôi ;-;

+2 Vì \(m^2+3\ge3\) thì để dấu = xảy ra tức là : \(m^2+3=3\) \(\Leftrightarrow m^2=0\)

<=> m = 0 .

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Đỗ Thanh Hải
11 phút trước

câu đâu e

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CC陈海南
10 phút trước

đề bài đâu bạn

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Đỗ Thanh Hải
2 phút trước

Thời gian cả hai xe đi từ lúc bắt đầu đến lúc gặp nhau là:

8 giờ 30 phút - 7 giờ = 1 giờ 30 phút = 1,5 giờ

Quãng đường xe đạp đi được từ lúc bắt đầu đến lúc gặp nhau là:

10 x 1,5 = 15 (km)

Quãng đường xe máy đi được từ lúc bắt đầu đến lúc gặp nhau là:

26 x 1,5 = 39 (km)

Quãng đường AB dài là: 

15 + 39 = 54 (km)

Đáp số : 54 km

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aannnn thiênnn

When referring to the overuse of antibiotics, the expression “too much of a good thing” can't help but come to mind. In many cases, antibiotics are absolutely necessary; for example, they can stop an ear infection from making you go deaf and they can even save your life after surgery. But why is it detrimental to take them too often?

 

Our immune system is our body’s first line of natural defense against infectious organisms. It protects us from bacteria and other microorganisms that can make us sick. In the past, people relied on their own bodies to cure them of illnesses, without the aid of medication or antibiotics. Nowadays, we often turn to antibiotics to do what our immune system used to do for us. And it’s not difficult to figure out why they're so popular. Antibiotics are an easy cure for many sicknesses and help the patient get out and about again in a very short time.

 

The problem is that, by relying too much on antibiotics, we are weakening our immune system. Just like our muscles, our immune system needs exercise to stay in shape. If it is not used, it becomes weaker, and thus increasingly more antibiotics are required to cure an illness. Years of overuse lead to a vicious cycle that is almost impossible to break.

The other important factor to consider is that our bodies contain both good and bad bacteria. The good bacteria are essential for our bodies to maintain a balance and in this way, prevent illnesses. They also help to fight off other bad bacteria which make us sick. Unfortunately, antibiotics cannot tell the difference between them, and once in our system, kill off both types. This again results in our getting sick more easily.

 

Question 71: What is the main purpose of the passage?

A. to explain why antibiotics are absolutely necessary

B. to argue that antibiotics do not allow people to recover

C. to warn people to be cautious with antibiotic use

D. to compare antibiotics to different types of therapy

 

Question 72: What is the relationship between the immune system and antibiotics?

A. They are both equally effective against infection.

B. They both work to fight off illnesses.

C. They are both a natural form of defense.

D. They both need time to cure the patient.

 

Question 73: According to the passage, why are antibiotics so well-liked?

A. They make our body stronger.                        B. They are easy to obtain.

C. They can cure all kinds of illness.                 D. They work very fast.

 

Question 74: How do antibiotics weaken our immune system?

A. They kill off bad bacteria.                                  B. They prevent us from getting exercise.

C. They do its work so it gets less efficient.    D. They decrease the strength of our muscles.

 

Question 75: in the third sentence of the fourth paragraph, what does they refer to?

A. illnesses                     B. our bodies                   C. antibiotics                   D. good bacteria

 

Đỗ Thanh Hải
12 phút trước

Question 71: What is the main purpose of the passage?

A. to explain why antibiotics are absolutely necessary

B. to argue that antibiotics do not allow people to recover

C. to warn people to be cautious with antibiotic use

D. to compare antibiotics to different types of therapy

Question 72: What is the relationship between the immune system and antibiotics?

A. They are both equally effective against infection.

B. They both work to fight off illnesses.

C. They are both a natural form of defense.

D. They both need time to cure the patient.

Question 73: According to the passage, why are antibiotics so well-liked?

A. They make our body stronger.                        B. They are easy to obtain.

C. They can cure all kinds of illness.                 D. They work very fast.

Question 74: How do antibiotics weaken our immune system?

A. They kill off bad bacteria.                                  B. They prevent us from getting exercise.

C. They do its work so it gets less efficient.    D. They decrease the strength of our muscles.

Question 75: in the third sentence of the fourth paragraph, what does they refer to?

A. illnesses                     B. our bodies                   C. antibiotics                   D. good bacteria

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Lam Tịch
8 phút trước

C B C C D

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a, Ta có : \(\sin\left(3x+60\right)=\dfrac{1}{2}\)

\(\Rightarrow3x+60=30+2k180\)

\(\Rightarrow3x=2k180-30\)

\(\Leftrightarrow x=120k-10\)

Vậy ...

b, Ta có : \(\cos\left(2x-\dfrac{\pi}{3}\right)=-\dfrac{\sqrt{2}}{2}\)

\(\Rightarrow2x-\dfrac{\pi}{3}=\dfrac{3}{4}\pi+k2\pi\)

\(\Leftrightarrow x=\dfrac{13}{24}\pi+k\pi\)

Vậy ...

c, Ta có : \(tan\left(x+\dfrac{\pi}{6}\right)=\sqrt{3}\)

\(\Rightarrow x+\dfrac{\pi}{6}=\dfrac{\pi}{3}+k\pi\)

\(\Leftrightarrow x=\dfrac{\pi}{6}+k\pi\)

Vậy ...

d, Ta có : \(\cot\left(2x+\pi\right)=-1\)

\(\Rightarrow2x+\pi=\dfrac{3}{4}\pi+k\pi\)

\(\Leftrightarrow x=-\dfrac{1}{8}\pi+\dfrac{k}{2}\pi\)

Vậy ...

 

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a) \(sin\left(3x+60^0\right)=\dfrac{1}{2}\)

\(\Leftrightarrow sin\left(3x+\dfrac{\pi}{3}\right)=sin\dfrac{\pi}{6}\)

\(\Leftrightarrow\left[{}\begin{matrix}3x+\dfrac{\pi}{3}=\dfrac{\pi}{6}+k2\pi\\3x+\dfrac{\pi}{3}=\dfrac{5\pi}{6}+k2\pi\end{matrix}\right.\)(\(k\in Z\))\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-\pi}{18}+\dfrac{k2\pi}{3}\\x=\dfrac{\pi}{6}+\dfrac{k2\pi}{3}\end{matrix}\right.\)(\(k\in Z\))

Vậy...

b) Pt\(\Leftrightarrow cos\left(2x-\dfrac{\pi}{3}\right)=cos\dfrac{3\pi}{4}\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-\dfrac{\pi}{3}=\dfrac{3\pi}{4}+k2\pi\\2x-\dfrac{\pi}{3}=-\dfrac{3\pi}{4}+k2\pi\end{matrix}\right.\)(\(k\in Z\))\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{13\pi}{24}+k\pi\\x=-\dfrac{5\pi}{24}+k\pi\end{matrix}\right.\)(\(k\in Z\))

Vậy...

c) Pt \(\Leftrightarrow tan\left(x+\dfrac{\pi}{6}\right)=tan\dfrac{\pi}{3}\)

\(\Leftrightarrow x+\dfrac{\pi}{6}=\dfrac{\pi}{3}+k\pi,k\in Z\)\(\Leftrightarrow x=\dfrac{\pi}{6}+k\pi,k\in Z\)

Vậy...

d) Pt \(\Leftrightarrow tan\left(2x+\pi\right)=-1\)

\(\Leftrightarrow2x+\pi=-\dfrac{\pi}{4}+k\pi,k\in Z\)

\(\Leftrightarrow x=-\dfrac{5\pi}{8}+\dfrac{k\pi}{2},k\in Z\)

Vậy...

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