Làm phép tính sau
3 phần 4 bằng x phần-4 bằng 21phần y bằng z phần 80
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\(1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}+\left(1+2+3\right)+...+\frac{1}{20}+\left(1+2+...+20\right)\)
= \(1+\frac{1}{2}.2.3:2+\frac{1}{3}.3.4:2+...+\frac{1}{20}.20.21:2\)
= \(\frac{2}{2}+\frac{3}{2}+...+\frac{21}{2}\)
=\(\frac{2+3+...+21}{2}\)
= \(\frac{230}{2}=115\)
Học tốt!
\(6x-7,2x=-14,4\)
\(\Leftrightarrow-1,2x=-14,4\)
\(\Leftrightarrow x=12\)
Vậy x = 12
Q(x) + ( 7 - x3 + 4x2 - x4 + x5 ) = x5 - x4 + x3 + 2x2 - 3x
Q(x) = x5 - x4 + x3 + 2x2 - 3x - ( 7 - x3 + 4x2 - x4 + x5 )
Q(x) = x5 - x4 + x3 + 2x2 - 3x - 7 + x3 - 4x2 + x4 - x5
Q(x) = 2x3 - 2x2 - 3x - 7
Ta có : \(Q\left(x\right)+\left(7-x^3+4x^2-x^4+x^5\right)=x^5-x^4+x^3+2x^2-3x\)
\(Q\left(x\right)=x^5-x^4+x^3+2x^2-3x-7+x^3-4x^2+x^4-x^5\)
\(Q\left(x\right)=2x^3-3x-7-2x^2\)
1. I cartoons best.
2. When do you go to bed last night.
3. If we use the car all the time, we will make the air dirty
4. I don't have a robot in my house
On my next vacation, I'm going to Da Lat with my family. Da Lat is called the land of fog. The tour will last 2 days. Our 2-day vacation plan is as followed. On the first day, I'll go for a walk around the hotel that I rented. My sister and I will enjoy all the food we love. My family and I will walk along the path to enjoy the scent of pine, grass, and flower. Then, we will go to the supermarket to buy some special food, tea, coffee, souvenir or go shopping and enjoy many other interesting activities. Early morning on the last day of vacation, we will go to the Poungour waterfall. The waterfall has a height of nearly 40 meters, spread over 100 meters, through a 7-story stone stair system. It's surrounded by a primeval forest with an area of about 2.5 ha with rich and diverse vegetation. The average temperature there ranging from 14 to 23 degrees celsius. In the evening, we'll visit our relatives. We'll be back the morning after. I'm excited about the upcoming vacation. Hopefully, the vacation will be as excited as I expected.
Sửa đề : \(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{40.43}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}\)
\(=1-\frac{1}{43}=\frac{42}{43}\)
So hs trg binh la : 45 . 2/9=10(hs)
So hs kha la : (45-10) : 100 . 60=21(hs)
So hs gioi la : 45-(21+10)=14(hs)
Ti so giua hs gioi va hs trg binh la : 14:10=1,4=140%
So hs gioi chiem so phan tram la : 14:45=0,31111....=31,1111%
\(\frac{3}{4}=\frac{x}{-4}=\frac{21}{y}=\frac{z}{80}\)
Vì \(\frac{3}{4}=\frac{x}{-4}\)\(\Rightarrow\frac{3}{4}=\frac{-x}{4}\)\(\Rightarrow-x=3\)\(\Rightarrow x=-3\)
Vì \(\frac{3}{4}=\frac{21}{y}\)\(\Rightarrow y=\frac{21.4}{3}=28\)
Vì \(\frac{3}{4}=\frac{z}{80}\)\(\Rightarrow z=80.\frac{3}{4}=60\)
Vậy \(x=-3\); \(y=28\); \(z=60\)