3 years ago

Write a formula for the sum of the first n integers that are divisible by 3

Mathematics

1 answer:

tino4ka555 [31]3 years ago

5 0

3*1+3*2+3*3+,,,+3n= 3*(1+2+...+n)
=3*n(n+1)/2

cause 1+2+...+n=n(n+1)/2

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Jaclyn has $120 saved and earns $40 each month in allowance. Pedro has $180 saved and earns $20 a month in allowance. If they bo

stich3 [128]

First, let's make an equation as to how to find how much money they have altogether:

(M stands for the # of month)

Jaclyn: 120 + 40m
Pedro: 180 + 20m

So let's plug-in 1 for m (1 will stand for 1 month)

Jaclyn: 120 + 40 * 1 = 160
Pedro: 180 + 20 * 1 = 200

I made a table depicting how much they'll make for the next 5 months (attached below). According to that, on month 3, they will have made the same amount of money (or $240).

So they will have the same amount of money in 3 months. Hope this helps! :)