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3 tháng 7 2021

B1: a)Dấu hiệu: Điểm ktra môn Toán của 1 nhóm hs

b)Điểm(x)    |  7  |  8  |  9  |  10  |

   Tần số(n) |  5  |  7  |  5  |     3  |  N=20

-Nhận xét: +Có 3 bạn đạt điểm cao nhất là 10 điểm

                  +Có 5 bạn điểm thấp là 7 điểm

                  +Có 20 bạn tham gia làm bài

c)AD CT tính số TBC:

     \(\dfrac{x_1.n_1+x_2.n_2+...+x_4.n_4}{N}\)

=\(\dfrac{7.5+8.7+9.5+10.3}{20}\)

=8,3

-Mo=8

 

Bài 4: 

a) Xét ΔCAE vuông tại C và ΔDAE vuông tại D có 

BE chung

AC=AD(gt)

Do đó: ΔCAE=ΔDAE(Cạnh huyền-cạnh góc vuông)

Suy ra: \(\widehat{CAE}=\widehat{DAE}\)(hai góc tương ứng)

mà tia AE nằm giữa hai tia AC,AB

nên AE là tia phân giác của \(\widehat{CAB}\)

b) Ta có: ΔCAE=ΔDAE(cmt)

nên EC=ED(hai cạnh tương ứng)

Ta có: BC=BD(gt)

nên B nằm trên đường trung trực của CD(Tính chất đường trung trực của một đoạn thẳng)(1)

Ta có: EC=ED(cmt)

nên E nằm trên đường trung trực của CD(Tính chất đường trung trực của một đoạn thẳng)(2)

Từ (1) và (2) suy ra BE là đường trung trực của CD(đpcm)

1 tháng 10 2021

máy tính hay tv đấy 

1 tháng 10 2021

Máy tính như hacker í

27 tháng 12 2018

24 - 16(x - 1/2) = 23

=> 16(x - 1/2) = 24 - 23

=> 16(x - 1/2) = 1

=> x - 1/2 = 1/16

=> x = 1/16 + 1/2

=> x = 9/16

27 tháng 12 2018

\(24-16(x-\frac{1}{2})=23\)

\(16(x-\frac{1}{2})=24-23\)

\(16(x-\frac{1}{2})=1\)

\(x-\frac{1}{2}=\frac{1}{16}\)

\(x=\frac{1}{16}+\frac{1}{2}\)

\(x=\frac{9}{16}\)

Vậy số thực x cần tìm là \(\frac{9}{16}\)

Chúc bạn hok tốt ~

9 tháng 1 2022

I am sorry, I can’t help you.” Peter said to me.

A.   Peter promised to help me.                          B. Peter refused to help me.                   

C. Peter asked me for help.                               D. I couldn’t help Peter.

To make Peter surprised, we _______ and when he comes, we ________.

A. are going to hide / will jump out and shout             B. will hide / are jumping out and shouting

C. are hiding / are going to jump out and shout          D. are hiding / are jumping out and shouting

26 tháng 12 2021

It’s kind of you to help me wash the dishes after the party.

A. Washing the dishes is kind of you to help me.

B. You are so kind when you help me wash the dishes.

C. To help me wash the dishes after the party you are kind.

D. It’s your kind to help me with the dishes after the party.

25 tháng 12 2016

chịu

 

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26 tháng 9 2023

So sánh:\(10^{10}\) và \(48.50^5\)

Ta có:

\(10^{10}=10^{2.5}=\left(10^2\right)^5=100^5=\left(2.50\right)^5=2^5.50^5=32.50^5\)

Vì \(32.50^5< 48.50^5\)

\(\Rightarrow10^{10}< 48.50^5\)

10 tháng 5 2017

Our Greener Would will able to have a clean air. It has many green trees around the Earth. Air around the world will not be able to pollute the air. People will not be affected by breathing. So, I love it so much.

Hơi ngắn

10 tháng 5 2017

Our green world will be able to have a clean air. It has many green trees around the Earth. Air around the world will not be able to pollute the air. People will not be affected by breathing. So, I love it so much.

18 tháng 9 2015

Cần gì , giúp được giúp cho

3 tháng 11 2021

bạn cần giúp gì,mình giúp cho nè 

3:

a: 5^n luôn có chữ số tận cùng là 5 với mọi n là số tự nhiên

=>5^100 có chữ số tận cùng là 5

b: \(2^{4k}\) có chữ số tận cùng là 6 với mọi k là số tự nhiên

mà 100=4*25

nên 2^100 có chữ số tận cùng là 6

c: 2023 chia 2 dư 1

mà \(9^{2k+1}\) luôn có chữ số tận cùng là 9

nên \(9^{2023}\) có chữ số tận cùng là 9

d: 2023 chia 4 dư 3

\(7^{4k+3}\left(k\in N\right)\) luôn có chữ số tận cùng là 3

Do đó: \(7^{2023}\) có chữ số tận cùng là 3

15 tháng 8 2023

Quy luật: 

+) các số có c/s tận cg là 0,1,5,6 nâng lên lũy thừa bậc nào (≠0) thì c/s tận cg vẫn là nó.

+) các số có tận cg là 2,4,8 nâng lên lt bậc 4n(n≠0) thì đều có c.s tận cg là 6.

+)các số có c/s tận cg là 3,7,9 nâng lên lt bậc 4n(n≠0)  thì đều có c/s tận cg là 1.

+) số có tận cg là 3 khi nâng lên lũy thừa bậc 4n+3 sẽ có tận cùng là 7

+) số có tận cg là 7 khi nâng lên lũy thừa bậc 4n+3 sẽ có tận cùng là 3

+) số có tận cg là 2 khi nâng lên lũy thừa bậc 4n+3 sẽ có tận cùng là 8

+) số có tận cg là 8 khi nâng lên lũy thừa bậc 4n+3 sẽ có tận cùng là 2

+) số có c/s tận cg là 0,1,4,5,6,9 khi nâng lên lũy thừa bậc 4n+3 thì c/s tận cg là chính nó

 

Bài 3: áp dụng quy luật bên trên

\(a.5^{100}=\overline{..5}\)     

\(b.2^{100}=2^{4.25}=\overline{..6}\)

\(c.9^{2023}=\overline{..9}\)  

\(d.7^{2023}=7^{4.505+3}=\overline{...3}\)

Bài 4:

\(A=17^{2008}-11^{2008}-3^{2008}\)

\(=\left(\overline{...7}\right)^{4.502}-\left(\overline{..1}\right)^{2008}-\left(\overline{..3}\right)^{4.502}\)

\(=\overline{..1}-\overline{...1}-\overline{...1}\)

\(=\overline{..9}\)

Bài 5:

\(M=17^{25}+24^4-13^{21}\)

\(=\left(\overline{..7}\right)^{4.6}.\left(\overline{..7}\right)+\left(\overline{..4}\right)^{4.1}-\left(\overline{..3}\right)^{4.5}.\left(\overline{..3}\right)\)

\(\overline{..1}.\overline{..7}+\overline{..6}-\overline{..1}.\overline{..3}\)

\(=\overline{...7}+\overline{..6}-\overline{..3}\)

\(=\overline{...0}\)

\(=>M⋮10\)