Answer:
1800
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Here a₁ = - 27 and d = 6, thus
=
[ (2 × - 27) + (29 × 6) ]
= 15( - 54 + 174)
= 15(120)
= 1800
Answer:

Step-by-step explanation:

It has to do with the number of dimensions you have in the figure. For example, in a square you have 2 dimensions, length and width. Since you have only two you use units^2. In a cube, you have 3 dimensions, length, width and height, which is where you get the units^3.