x²-4x-9=29
You need to complete the square by following the next few steps.
First, you need to place the x²-4x into squared brackets, by dividing the coefficient of x by 2x and dividing x² by x:
(x-2)²
Find out what this equals to:
x²-4x+4
We can start off here, as we have obtained the x²-4x. However, we need to get from +4 to -9. To do this, we must minus 13. Therefore, our equation now looks like this:
(x-2)²-13=29
Now, just solve as you normally would, to isolate x:
(x-2)²-13=29
Add 13 on both sides
(x-2)²=42
Square root both sides
x-2=±√42
Add 2 on both sides
x=2±√42
So, your answer is the first option
