\(P=\left\{13;16;19;...;97\right\}\)

Số số hạng là: (97-13):3+1=29(phần tử)

P=(x \(\in\) N/xϵ Số lẻ có 2 chữ số)

p={13;16;19;...;97}

số số hạng là:(97-13):3+1=29 ( phần tử )

Vì 1⁵= 1⁶ nên x - 5 = 1

x= 1+5

x=6

\(\left(x-5\right)^5=\left(x-5\right)^6\)

\(\Rightarrow\left(x-5\right)^6-\left(x-5\right)^5=0\)

\(\Rightarrow\left(x-5\right)^5\left(x-6\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\x=6\end{matrix}\right.\)

\(\left(x-5\right)^5=\left(x-5\right)^6\)

\(\Rightarrow\left(x-5\right)^6-\left(x-5\right)^5=0\)

\(\Rightarrow\left(x-5\right)^5.\left(x-5-1\right)=0\)

\(\Rightarrow\left(x-5\right)^5.\left(x-6\right)=0\)

\(\Rightarrow\left\{{}\begin{matrix}\left(x-5\right)^5=0\\x-6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=5\\x=6\end{matrix}\right.\)

hậu quả của bệnh đao ở thể 3 nhiễm của 1NST số21

làm mất cân bằng toàn hệ gen → cơ thể không sống được hay giảm sức sống, giảm khả năng sinh sản.

\(\left(\dfrac{1}{\sqrt{a}-1}-\dfrac{1}{\sqrt{a}}\right):\left(\dfrac{\sqrt{a}+1}{\sqrt{a}-2}-\dfrac{\sqrt{a}+2}{\sqrt{a}-1}\right)\)

\(=\left(\dfrac{\sqrt{a}}{\sqrt{a}\left(\sqrt{a}-1\right)}-\dfrac{\sqrt{a}-1}{\sqrt{a}\left(\sqrt{a}-1\right)}\right):\left(\dfrac{\left(\sqrt{a}+1\right)\left(\sqrt{a}-1\right)}{\left(\sqrt{a}-2\right)\left(\sqrt{a}-1\right)}-\dfrac{\left(\sqrt{a}+2\right)\left(\sqrt{a}-2\right)}{\left(\sqrt{a}-1\right)\left(\sqrt{a}-2\right)}\right)\)

\(=\dfrac{\sqrt{a}-\sqrt{a}+1}{\sqrt{a}\left(\sqrt{a}-1\right)}:\left(\dfrac{a-1}{\left(\sqrt{a}-2\right)\left(\sqrt{a}-1\right)}-\dfrac{a-4}{\left(\sqrt{a}-1\right)\left(\sqrt{a}-2\right)}\right)\)

\(=\dfrac{1}{\sqrt{a}\left(\sqrt{a}-1\right)}:\dfrac{a-1-a+4}{\left(\sqrt{a}-2\right)\left(\sqrt{a}-1\right)}\)

\(=\dfrac{1}{\sqrt{a}\left(\sqrt{a}-1\right)}:\dfrac{3}{\left(\sqrt{a}-2\right)\left(\sqrt{a}-1\right)}\)

\(=\dfrac{1}{\sqrt{a}\left(\sqrt{a}-1\right)}.\dfrac{\left(\sqrt{a}-2\right)\left(\sqrt{a}-1\right)}{3}\)

\(=\dfrac{\sqrt{a}-2}{3\sqrt{a}}\)

Đường kính AB

lai 

Đường kính AB 

I had a trip to Da Lat with my classmates in three days last year on the summeroccasion. The trip was started at 9 am, we travelled by plane. I felt so happy becauseI believed that I would have a good time with my friends. We arrived in Da Lat at 11 am.We had lunch, and then prepared for the camp-fire at night. In the afternoon,we climbed the Langbiang mountain and took many pictures. We stood in a circle-around the camp-fire, and had a lot of activities with ethnic minority people such as:performing dances, singing, drinking wine, etc.The second day, we visited the church. We took some pictures together andbought some souvenirs. In the last day, we came to the Golden Valley. At the end of the trip, we felt this place was wonderful and exciting and had lots of beautiful scenery and wonderful natural scenery. After the trip I learned that there are many places to explore and enjoy life better because life is very short so people have to thoroughly enjoy not to waste life. (Ai có quan điểm về bài học rút ra khác thì trả lời bên dưới nha ^.^)

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Van Tu , Thuong Tin , Ha Noi

November 9 , 2017

Dear Donna ,

Thanks for your letter . I'm pleased to hear you had a great time on Mother 's Day .

We received our second semester report last month . I got good grades for Geography , Physics and Math . But my teacher told me to improve English and History .

In a few days , the Mid-Autumn Festival is coming or call it the moon festival . I'm going to Ha Long Bay with my aunt and uncle by bus this afternoon . I'll send you a postcard from there .

Write soon and tell me all your news .

Your friends ,

Lan .