1. Use the FOIL method (x+9)(x+9)
First, outer, inner, last

Add your like terms

2. When you add or subtract polynomials you add or subtract the like terms and then put them in order from largest to smallest exponents.
3.

4. Since it is the perimeter, we add the 3 together.

Add the like terms together:

Put them in order of exponents

Hope this helps
Well first you need to show the rest of the problems before i can truely help you sorry.
Answer:
51.6666666667
Step-by-step explanation:
Answer:
can
Step-by-step explanation: ;)
Answer:
810 is 100 times the size of 0.81