Question

How do you solve using the completing the square method `3x^2 – x – 1 = 0`?

Answer 1

Solution: `x = 1/6((1+-sqrt13)`

Explanation:

`3x^2-x-1 =0 or 3( x^2-x/3) -1 = 0 or 3( x^2-x/3) =1`

or `3( x^2-x/3 +(1/6)^2) =1+3/36 or 3(x-1/6)^2=1+1/12`

or `3(x-1/6)^2=13/12 or (x-1/6)^2=13/36` or

`(x-1/6)=+- sqrt(13/36) or x = 1/6 +- sqrt13/6` or

`x = 1/6((1+-sqrt13)`

Solution: `x = 1/6((1+-sqrt13)` [Ans]