Answer:
c
Step-by-step explanation:
Using Pascal's triangle, the expansion, although EXTREMELY lengthy, will help you find the 7th term. I am going to type out the expansion only up til the 7th term (although there are actually 10 terms because we are raised to the power of 9). If you would like to learn how to use Pascal's Triangle for binomial expansion, you will need to visit a good website that explains it because it's just too difficult to do it via this website.
The expasion is as follows (up to the 7th term):

That last term is the 7th term. You find out its value by multiplying all the numbers together and adding on the c^3d^6. Again those come from Pascal's triangle, and it's one of the coolest math things ever. I encourage you to take the time to explore how it works.
The exclamation points mean factorial which is when you multiply that number along with the numbers less than it. Ex: 4! = 4*3*2*1. To solve this, you must get those factorials and after you solve, you get 60480
Answer:
-1
Step-by-step explanation:
C. You'd be starting at a higher floor (positive number) and descending floors (negative number per x). If you assume x is time it's a little more logical and visual.
Answer:
B
Step-by-step explanation:
3 rectangles are 3 x 7 x 2 = 42
2 triangles are 2 x 1/2 x 2 x
= 2
note that you have to use Pythagoras Theorem to solve for the height of the triangle