Question

How do you solve `4x^2-2x-5=0` by completing the square?

Answer 1

`4x^2 - 2x - 5 = 4x^2 - 2x + 1/4 - 5 - 1/4 =`
`(2x - 1/2)^2 = 5 + 1/4 = 21/4`

a. #(2x - 1/2) = (sqr21)/2 -> 2x = 1/2 + (sqr21)/2 ->

`x = 1/4 + (sqr21)/4`

b. `(2x - 1/2) = -(sqr 21)/2 -> 2x = 1/2 - (sqr21)/2` ->

`x = 1/4 - (sqr21)/4`