9514 1404 393
Answer:
B, D
Step-by-step explanation:
The quadratic expands to ...
(2n -1)² = (2n)² +2(2n)(-1) +(-1)² = 4n² -4n +1
The coefficients can be factored out of the sum, so ...
∑(4n²) = 4∑n² for example
The sum of 60 ones is 60:

So, the sum can be written as ...

_____
It appears that the key to choosing the correct answers is paying attention to signs.
Answer:
Step-by-step explanation:
Find the sum of the first 42 terms of the following series, to the nearest integer.
2,7,12
Solution
The sum is given by
SUM_n=n/2*(a_1+a_n)
a_n=a_1+(n-1)d
a_1=2, n=42, d=5
The 42nd term is therefore given by
a_42=2+(42-1)5=207
SUM_42=42/2*(2+207)=21*209=4389
The sum of the first 42 terms of the series, therefore, is 4389
The mean of the data set is 6.8.
<h3>What is the mean?</h3>
Mean is the average value of the given set of observations. In statistics, we also come across different types of mean such as Arithmetic, Geometric and Harmonic mean.
Given
The data set is 14, 7, 2, 8, 3.
The mean of the data set is given by;

Hence, the mean of the data set is 6.8.
To know more about mean value click the link given below.
brainly.com/question/4209766
i know the answer it's the first one
on the left
3.2(s+10)=32
3.2s+20=32
6s+20=32
6s=12
s=2