Investment of $20,000, part at 3% interest and part at 5% interest, investment returned $800, how was the original $20,000 investment split between the two interest rates?

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for

5

step-by-step explanation:

the eight graders whould be the answer

step-by-step explanation: could you give me 5 stars