Question #fef3e

1 Answer
Apr 24, 2017

We can solve this by the factoring method.
[This video explains solving by factoring very well if you are still lost after this explanation.](https://www.khanacademy.org/math/algebra/quadratics/solving-quadratic-equations-by-factoring/v/example-1-solving-a-quadratic-equation-by-factoring)

x^2+13x+42x2+13x+42

Looking at this quadratic equation we need to find two numbers that when multiplied give us "42"42 and when added give us "13"13
So,

x*y=42xy=42

AND

x+y=13x+y=13


In this case, your two numbers are 6 and 7

6*7=4267=42

6+7=136+7=13

This means we have (x+6)(x+7)(x+6)(x+7)
but our final answer is x=-6, -7x=6,7

Think of it like this...
We have:

x+6=0x+6=0

AND

x+7=0x+7=0

So we need to move our numbers to the right side of the equals sign to get the value of x. That is why they are negative.

x=-6x=6

x=-7x=7