Question

Solve the equation by completing the square.
6x^2-x-5=0

So far i got
x^2-1/6x-5/6=0
x^2-1/6x=5/6
Now i dont understand this step by
add the square of half of -1/6 to both sides
I dont understand what that means please help

Answer 1

why?....

Answer 2

Cant we just factor it?

Answer 3

okay

Answer 4

@Tyler1204 ?

Answer 5

@pooja195 i have the steps and it says add the square of half of -1/6 to both sides but i dont understand how that answer is 1/144

Answer 6

hmm im not sure how to do it that way @Loser66 might know :3

Answer 7

This is what it says by the way http://prntscr.com/7dnq4a

Answer 8

you are good until \(x^2 -(1/6)x -(5/6)=0\)
Now, I pick the middle term to say, ok? to have a complete the square, you have formula
\((x-a)^2 = x^2 -2ax+a^2\) right? your middle term is (1/6) x, right?

Answer 9

so, to find a, the term we need to have the complete square, I do
\(2a x = \dfrac{1}{6}x\), hence \(2a=\dfrac{1}{6}\), so \(a =\dfrac{1}{12}\) so far so good?

Answer 10

erm erm @Loser66 ok like what you saying sounds good lol but like i have to follow this way :S did you see the picture i posted ? http://prntscr.com/7dnq4a

Answer 11

Now, the original one
\(x^2 -2 (\dfrac{1}{12}) x +\color{red}{(\dfrac{1}{12})^2} - \color{red}{(\dfrac{1}{12})^2}-\dfrac{5}{6}=0\)

Answer 12

@Tyler1204 it is not "sounds good". I explained you why 1/144 appears.

Answer 13

OH OH erm ok let me re read then lol sorry

Answer 14

You killed my feeling.

Answer 15

Grrr im still confused because for me it dos not say anything about that formula you said :/ (x-a)^2=x^2-2ax+a^2
Did you open the picture? because like i have to follow what it says :S

Answer 16

@Loser66