Answer:


Step-by-step explanation:
<u>Equations</u>
We have two cases where some variable is required to be found such that some condition is met. The first case is about finding the value of a that complies:

Rearranging

Factoring:

There are two solutions:

The second case requires us to find the value of x such that

Rearranging

This second-degree equation has no real roots. We'll offer the imaginary (complex) solutions:

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Answer:
A = x^2 + 4x -21
Step-by-step explanation:
L = x+7
W = x-3
A = L*W
A = (x+7)(x-3)
A = x^2 + 4x - 21