Which of the following is a geometric series? 0.1 + 0.3 + 0.5 + 0.7 1 + 3 + 9 + 27 19 + 17 + 15 + 13 0.4 + 0.9 + 1.5 + 2.2

The answer is the second option.

This is because it multiplies 3 up to the figures consistently as the series progresses.

1 x 3 = 3
3 x 3 = 9
9 x 3 = 27

Hope this helps. - M

The first one is not a geometric series, because the equation is y=0.2x-0.1, it is an arithmetic series.
The second one is a geometric series, because the equation is y=3^(x-1)
The 3rd one is not, because the equation is y=19-2x, and, again, it is arithmetic.
The 4th one is not a geometric series, but rather a recursive sequence.
Hope this helps. 

4x^2+16x+5

Step-by-step explanation:

(6x^2+7x)+(5-2x^2+9x)

6x^2-2x^2+7x+9x+5

4x^2+16x+5