1. The area of a square is calculated by squaring the measure of a side. Thus, a square with an area of x^2 has sides of length x. By extending all sides by 6, we can now get its area by (x + 6)(x + 6) = (x + 6)^2 = x^2 + 12x + 36 square units
Take note that (a + b)^2 = a^2 + 2ab + b^2. How? Try deriving that from the FOIL(First, Outer, Inner, Last) Method
2. (5x^4 - 2)(5x^4 + 2) Observe that that is in the form of (a + b)(a - b).
Now, if you're familiar with a^2 - b^2, or the difference of two squares, you'll know that a^2 - b^2 can also be expressed as (a + b)(a - b). Now, our lives definitely got easier ;)
Thus, (5x^4 - 2)(5x^4 + 2) = (5x^4)^2 - (2)^2 = 25x^8 - 4
If you have any questions, don;t hesitate to ask :)