Question

x2 + 6x + 8 = 0

Answer 1

try factoring first

Answer 2

Do you want to use factoring? or the quadratic formula?

Answer 3

factoring , im just not good at this

Answer 4

Ok, so you are looking for two numbers a, and b where they add to give you the middle coefficient and multiply to give you the last coefficient.

What two numbers can you multiply to make 8 and add to make 6?

Answer 5

wait , im not understanding what that says ^

Answer 6

Ok well we know that we are looking for something like:

\[(x+a)(x+b)\]
Right?

Answer 7

right

Answer 8

Ok well if we foil that out we will get:

\[(x+a)(x+b) \]\[= x^2 + ax + bx + ab \]\[= x^2 + (a+b)x + ab\]

And that must equal our original expression:
\[x^2 + 6x + 8\]

Therefore the middle term \((a+b)x\) must equal 6x so\[a+b = 6\]
And \(ab\) must equal our last term 8, so we have
\[a\times b = 8\]

So if we can figure out what two numbers multiply together to make 8 and add together to make 6, we will know our a and b.