<span>a2 – b2 = (a + b)(a – b) or (a – b)(a + b).
This is the 'Difference of Squares' formula we can use to factor the expression.
In order to use the </span><span>'Difference of Squares' formula to factor a binomial, the binomial must contain two perfect squares that are separated by a subtraction symbol.
</span><span>x^2 - 4 fits this, because x^2 and 4 are both perfect squares, and they are separated by a subtraction symbol.
All you do here to factor, is take the square root of each term.
√x^2 = x
√4 = 2
Now that we have our square roots, x and 2, we substitute these numbers into the form (a + b)(a - b).
</span>
<span>(a + b)(a - b)
(x + 2)(x - 2)
Our answer is final </span><span>(x + 2)(x - 2), which can also be written as (x - 2)(x + 2), it doesn't make a difference which order you put it in.
Anyway, Hope this helps!!
Let me know if you need help understanding anything and I'll try to explain as best I can.</span>
Answer: 
Step-by-step explanation:
For this exercuse you need to analize the information provided. You know that:
1) The height of the replica of the Empire State Building with its antenna spire in Las Vegas is 485 feet.
2) The height of the real Empire State building is 1,454 feet.
Finally, in order to find the ratio of height of the replica to the height of the real Empire State building, its necessary to divide the height of the replica of the Empire State Building by the height of the real Empire State building.
Therefore, trough this procedure you get that the ratio of height of the replica to the height of the real Empire State building is:

(This fraction cannot be reduced)
To convert any unit to it's "milli-" form always multiply the given value by 1000. The new value will be the value of in the "milli-" form.
The question asked to us is to convert 3.521 g to mg (or milligram). Thus, all that we need to do is to multiply 3.521 with 1000 and we will get the corresponding value in milligrams. Thus, in mg, 3.521 g is:
mg
Answer:
21
Step-by-step explanation:
14+7=21
Answer:
≈ 4.89
Step-by-step explanation:
A = πr²
75 = 3.14 x r²
r² = 75 / 3.14 = 23.89
r = 4.89