My best mistake was when I thought I could factor out -1 to make a perfect square. What I didn’t see is that I can’t do that because 9x is not a perfect square. 9 is, but x isn’t so it can’t be considered perfect.

This was my incorrect work.

Here is the correct way:

What I did first was to move the 4×2 to the left, I did this because I prefer it to be in that order.

Then I factored out x and -1 because I don’t want the coefficient in front of x2 to be negative.

After this I have x=0, and x= 9/4 which are correct.

Remember that everything needs to be a perfect square and subtraction to factor using perfect square method!!