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:
30
Step-by-step explanation:
24/8 = 3
18/6= 3
10x3 = 30
Answer:
y = (1/4)x
Step-by-step explanation:
"Direct variation" here signifies y = kx, where k is the constant of proportionality.
Then y = kx. Here we are to find k using the info that x = 12 and y = 3:
3 = k(12), or
k = 3/12, or k = 1/4
Then y = (1/4)x
13 factored out is 13x - 39 add 39 to both sides it equals 13x=78 and 78 divided by 13 is 6 the anwser is x=6
