-18
1) Distribute the -6 to the parentheses
-4 - (6*7) - (-6*3)
2) Simplify
-4 - 42 + 18
-18
By synthetic division, the quotient (4x^2 -10x -24)/(2x +3) is 2x -8.
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You have not actually said what division you want performed.
The domain of the function is \[A \ge0\] If A is negative we get an imaginary number for the radius. This makes sense because the area of a circle cannot be negative.
X>-4 would be the correct answer