It is asking you to find the sum of k^2 - 1 from k=1 to k=4. Since that is only 4 numbers, calculating the sum by hand wouldn’t be that bad.
(1^2 - 1) + (2^2 - 1) + (3^2 - 1) + (4^2 - 1) = 26
The easier way to find the sum is to use a few simple formulas.
When we have a term that is just a constant c, the formula is c*n.
When we have a variable k, the formula is k*n*(n+1)/2.
When we have a squared variable, the formula is k*n*(n+1)*(2n+1)/6.
In this case, we have a squared variable k^2 and a constant of -1.
So plug in n=4 to the formulas:
4*5*9/6 - 1*4 = 26
The answer is 26
The answer is = because of you take away the 0 in the decimal 8.250 it's the same decimal as 8.25 and in decimals the zeros farthest to the right don't matter.
8.25 = 8.250
Answer: Sal used a debit card and paid a total of $324.80 for the stereo. (I took the test too)
Step-by-step explanation: Multiply $21.30 by 18 months. Then subtract the interest, $58.60, from the product because Sal paid immediately with a card which implies using a debit card. You get $324.80.
Answer:
This sum is the sum of an arithmetic sequence. There is a formula for the sum of an arithmetic sequence which can be looked up or derived by a variety of means.
A nice approach for this sequence is the following. Notice that the sum of first and last number in the sequence is the same as the sum of the second and second last, and also the same as the sum of the third and third last, and so on.
There are n of these pairs. So the desired sum is n x (first number + last number). But the first number is 1 and the last on is 2n. Thus the desired sum is n(1 + 2n).
Hope this helps!!
Mark Brainleast!!!!!!!!!!!
Answer:
$54.75
Step-by-step explanation:
0.05 x 365 = 18.35
18.25 x 3 = 54.75
