Question

How do you solve using the completing the square method `2x^2 = 2x + 15`?

Answer 1

Solution : `x= 1/2(1 + sqrt(31)) and x= 1/2(1 - sqrt(31))`

Explanation:

`2x^2 =2x+15 or 2x^2 -2x= 15 or 2(x^2-x) =15 or (x^2-x) = 15/2`or

`(x^2-x +(1/2)^2) -1/4= 15/2 or (x-1/2)^2 = 15/2+1/4 or (x-1/2)^2 = 31/4` or
`(x-1/2)= +-sqrt(31/4) or x = 1/2+- sqrt(31)/2 or x = 1/2(1 +- sqrt(31))`

Solution : `x= 1/2(1 + sqrt(31)) and x= 1/2(1 - sqrt(31))` [Ans]