Question

How do you solve the quadratic equation by completing the square: `x^2 - 3x = 4`?

Answer 1

I found:
`x_1=-1`
`x_2=4`

Explanation:

You can try adding and subtracting `9/4` on the left side:
`x^2-3xcolor(red)(+9/4-9/4)=4`
rearranging:
`x^2-3x+9/4=4+9/4`
`(x-3/2)^2=(16+9)/4`
square root both sides:
`x-3/2=+-sqrt(25/4)=+-5/2`
So, you get two solutions:
`x_1=5/2+3/2=4`
`x_2=-5/2+3/2=-1`