Answer: it would be four
Step-by-step explanation:
The sum of the series 
is 44.
Step-by-step explanation:
The given series is 
To find the sum of the series, we need to substitute the values for k in the series.
![\sum_{k=1}^{4}\left(2 k^{2}-4\right)=\left[2(1)^{2}-4\right]+\left[2(2)^{2}-4\right]+\left[2(3)^{2}-4\right]+\left[2(4)^{2}-4\right]](https://tex.z-dn.net/?f=%5Csum_%7Bk%3D1%7D%5E%7B4%7D%5Cleft%282%20k%5E%7B2%7D-4%5Cright%29%3D%5Cleft%5B2%281%29%5E%7B2%7D-4%5Cright%5D%2B%5Cleft%5B2%282%29%5E%7B2%7D-4%5Cright%5D%2B%5Cleft%5B2%283%29%5E%7B2%7D-4%5Cright%5D%2B%5Cleft%5B2%284%29%5E%7B2%7D-4%5Cright%5D)
Now, simplifying the square terms, we get,
![[2(1)-4]+[2(4)-4]+[2(9)-4]+[2(16)-4]](https://tex.z-dn.net/?f=%5B2%281%29-4%5D%2B%5B2%284%29-4%5D%2B%5B2%289%29-4%5D%2B%5B2%2816%29-4%5D)
Multiplying the terms,
![[2-4]+[8-4]+[18-4]+[32-4]](https://tex.z-dn.net/?f=%5B2-4%5D%2B%5B8-4%5D%2B%5B18-4%5D%2B%5B32-4%5D)
Subtracting the values within the bracket term, we get,
Now, adding all the terms, we get the sum of the series,
Thus, the sum of the series is
Is it adding or subtracting
Answer:
x = 3/10
Step-by-step explanation:
−1/2 − (−4/5) = x
First, switch sides.
x = −1/2 − (−4/5)
You are subtracting a negative number. Subtracting a negative number means add a positive number.
x = -1/2 + 4/5
Now you are adding two fractions, so you need a common denominator. The LCD of 2 and 5 is 10.
x = -5/10 + 8/10
x = 3/10
Answer:
85%
Step-by-step explanation:
If she got 3 wrong then it means she got 20-3 right, so she got 17 questions right.
From there we get the fraction: 17/20
To make the a percentage we times both the top and bottom by 5 (because 20 x 5 = 100)
By doing that we get 17x5/20x5
= 85/100
That is equal to 85%
