Question 192455
Factor:
{{{9x^2+4y^2}}} This is not factorable into rational factors.
The only way that you can factor this is with irrational factors:
{{{9x^2+4y^2 = (3x-2yi)(3x+2yi)}}} where {{{i = sqrt(-1)}}}
To see this, multiply the two factors given above using the FOIL method:
{{{(3x-2yi)(3x+2yi) = 9x^2+6xyi-6xyi-4y^2i^2}}}
But {{{i^2 = -1}}} so make this substitution...
{{{9x^2+6xyi-6xyi-4y^2i^2 = 9x^2+4y^2}}}