How do you factor #y= x^2 - 10x - 9# ?
We need to look for numbers whose SUM is
The pairs we could use to have a product of
This means the expression is PRIME, if we limit ourselves to integers.
However, if we throw irrationals into the mix, we can use the quadratic formula or complete the square to find this quadratic's irrational roots.
Thus, the roots of this are
Normally, if a root were, say,
You could rewrite
We can do the same for the irrational monstrosity we have:
Thus, factored, we get