Which formula represents the partial sum of the first n terms of the series: 2 + 6 + 10 + + (4n - 1)?
a) 4n^2 + 2n
b) 4n^2 + 1/2n
c) 2n^2 + 2n
d) 2n^2 + 1/2n

will give brainlist and 15 points to correct answer. .

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.

Four thousand nineteen hundred thousandths in standard form is 4900