50+50:2
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Đề bài:25x2+50+50:0.25+50:0.5+50:0.125+50:0.25
=50+50+50x4+50x2+50x8+50x4
=50x(1+1+4+2+8+4)
=50x20
=1000
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có :
\(A=\dfrac{50}{111}+\dfrac{50}{112}+\dfrac{50}{113}+\dfrac{50}{114}\)
Ta thấy :
\(\dfrac{50}{111}>\dfrac{50}{200}\)
\(\dfrac{50}{112}>\dfrac{50}{200}\)
\(\dfrac{50}{113}>\dfrac{50}{200}\)
\(\dfrac{50}{114}>\dfrac{50}{200}\)
\(\Rightarrow A>\dfrac{50}{200}+\dfrac{50}{200}+\dfrac{50}{200}+\dfrac{50}{200}\)
\(\Rightarrow A>\dfrac{50}{200}.4=1\) \(\left(1\right)\)
Mặt khác :
\(\dfrac{50}{111}< \dfrac{50}{100}\)
\(\dfrac{50}{112}< \dfrac{50}{100}\)
\(\dfrac{50}{113}< \dfrac{50}{100}\)
\(\dfrac{50}{114}< \dfrac{50}{100}\)
\(\Rightarrow A< \dfrac{50}{100}+\dfrac{50}{100}+\dfrac{50}{100}+\dfrac{50}{100}\)
\(\Rightarrow A< \dfrac{50}{100}.4=2\) \(\left(2\right)\)
Từ \(\left(1\right)+\left(2\right)\Rightarrow1< A< 2\rightarrowđpcm\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
= [ 50 x ( 76 - 24 + 22)] x 2
= 50 x 74 x 2
= (50 x 2) x 74
= 100 x 74
= 7400.
![](https://rs.olm.vn/images/avt/0.png?1311)
là 6375
hãy k nếu bạn thấy đây là câu tl đúng :)
chúc bạn hok tốt :P
1 + 1 + 1 + 1 + 1 + 2 + 2 + 2 + 2 + 2 +...+ 50+50+50+50
= 1x5 + 2x5 + 3x5 +...+50x5
=5x(1+2+3+...+50)
=5x1275
=6375
\(50+50:2\)
\(=50+25\)
\(=75\)
75 nha b ạn