The answer is because 3 squared =9
Answer:

The solution set is 
Step-by-step explanation:
we have

Solve for x
Subtract
both sides


Divide by
both sides


The solution is the interval-------> 
All real numbers greater than 
This would be 3990 if you require a whole number but for a decimal it would be 3989.24
The answer is correct because it would have to go like this;
(-4x + 9)² = (-4x + 9)(-4x + 9)
hope this helps, God bless!