Answer:
Hello,
Step-by-step explanation:
Part A: see picture
Part B: see picture
Part C:
You must remenber :
![\displaystyle \sum_{i=1}^{n} i= \dfrac{n*(n+1)}{2} \\\\\displaystyle \sum_{i=1}^{n} i^2= \dfrac{n*(n+1)(2n+1)}{6} \\\\\\\int\limits^{20}_0 {(20\ x-x^2)} \, dx =[\dfrac{20\ x^2}{2} -\dfrac{x^3}{3} ]^{20}_0=\dfrac{20^3}{3} =1333.\overline{3}\\\\\\](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Csum_%7Bi%3D1%7D%5E%7Bn%7D%20i%3D%20%5Cdfrac%7Bn%2A%28n%2B1%29%7D%7B2%7D%20%5C%5C%5C%5C%5Cdisplaystyle%20%5Csum_%7Bi%3D1%7D%5E%7Bn%7D%20i%5E2%3D%20%5Cdfrac%7Bn%2A%28n%2B1%29%282n%2B1%29%7D%7B6%7D%20%5C%5C%5C%5C%5C%5C%5Cint%5Climits%5E%7B20%7D_0%20%7B%2820%5C%20x-x%5E2%29%7D%20%5C%2C%20dx%20%3D%5B%5Cdfrac%7B20%5C%20x%5E2%7D%7B2%7D%20-%5Cdfrac%7Bx%5E3%7D%7B3%7D%20%5D%5E%7B20%7D_0%3D%5Cdfrac%7B20%5E3%7D%7B3%7D%20%3D1333.%5Coverline%7B3%7D%5C%5C%5C%5C%5C%5C)
We divide the intervalle in n equal parts:


Answer:
Scalene
Explanation:
It isn’t equilateral or isosceles. Therefore it must be scalene
Answer:
He is about 6 years old (5 years 11 months)
Step-by-step explanation:
13 - 7 and 3 - 2
Answer:
Step-by-step explanation:
option (d) 4hrs 40mins