Answer:
Step-by-step explanation:
Here is another method. It might be shorter. You can decide. Make sure that the numbers are odd by doing this
2k + 1 is one of the odd numbers. 2k is even. When you add 1 to 2k + 1 is odd.
2k - 1 is another member of this family
2k + 3 is a third member
2k - 3 is the fourth member.
When you add them, all the coefficients will cancel out.
2k + 1 + 2k - 1 + 2k - 3 + 2k + 3 = 400 Add
8k = 400 Divide by 8
k = 400/8
k = 50
2k + 1 = 2*50 + 1 = 100 + 1 = 101
2k - 1 = 2*50 - 1 = 100 - 1 = 99
2k + 3 = 2*50 + 3 = 103
2k - 3 = 2*50 - 3 = 97
You don't really need to use 2k. You can do the same thing with n - 1 and n + 1 and n - 3 and n + 3. The same thing will happen: all the coefficients will cancel.
and r into the formula.
