Can you please add the picture with the problem, then I will answer your question ?
Rectangle:
A=l(w)
A=12(6)
A=72cm^2
Semicircle:
r=6/2
r=3
A=(3.14(r)^2(1/2)
A=3.14(3)^2(1/2)
A=3.14(9)(1/2)
A=14.13cm^2
A=14.1cm^2
Total area: 72cm^2 + 14.1cm^2 = 86.1cm^2
For an explicit formula in its simplified form, we must evaluate the first two terms.
For
,
, and
. We see that the common difference is
, and
, so we write,
.
The correct answer is
B.