2(4a^2 +a +3)
Factor out the 2
Answer:
i think its just the last one
Step-by-step explanation:
because the first two are all real numbers and the thrid equals one
A quadrilateral I believe.
For sake of convenience, reverse the series, then it would be:
21,19,17.....7
a=21, d = -2,
s(4) = 4/2 (21+15)
s(4)=2(36)
s(4) = 72
