I am assuming you wrote the problem wrong. Is it a^2?
A^2 -4A-21=0
(A-7)(A+3)=0
A=7 A=-3, ignore the negative number because it doesn't make sense if you plug in for a.
length=a+3=7+3=10
Width=7=a
<span>Difference of squares method is a method that is used to evaluate the difference between two perfect squares.
For example, given an algebraic expression in the form:
can be factored as follows:

From the given expressions, the only expression containing two perfect squares with the minus sign in the middle is the expression in option A.
i.e.

which can be factored as follows:

.</span>
Answer:
Variable A and variable B have a negative linear association.
Step-by-step explanation:
We are asked to find which best describes the association between variable A and variable B.
From the scatter plot we could clearly see that as the value of variable A are increasing the corresponding value of variable B is decreasing.
Also we could see that the points are linear.
Hence, the relationship that best describes variable A and variable B is:
Negative linear Association
The discriminant of this equation is 49. The solutions for this equation are x=2 and x=-

I hope that helps.
Answer:
Your answer is that the magazine would cost $1.33 per issue.
Step-by-step explanation:
There are 12 months in a year and we get one issue per month, so we need to divide the cost 15.96 by 12 to find out the price per month. Your answer is that the magazine would cost $1.33 per issue.