Answer:
[tex]\frac{1+3(n-1)}{3+4(n-1)}[/tex]
Step-by-step explanation:
First find the pattern.
1/3 gets 5/21 added to it but doing that to 4/7 does not get 7/11, so it's nto normal adding.
if you multiply 1/3 gets 12/7, but if you multiply that by 4/7 you don't get 7/11 so it's not normal multiplcation.
I would next try only adding to the numerator and denominator separately.
so 1/3 gets 3 added to the 1 and 4 added to the 3. Doing that again gets us (4+3)/(7+4) = 7/11 and doing it again gets us 10/15 = 2/3. So that is the right answer.
So we know what is happening. if you start with 1/3 and increasingthe numerator by 3 and denominator by 4 then we know it's going to look like (1+3(n-1))/(3+4(n-1)) because the first term is when n=1 and we want that to cancel out. You can also simplify it and get (3n-2)/(4n-1)
Let me know if it doesn't make sense.