simplify the equation 3xsquared-4xy+ysquared /9xsquared -ysquared
(3x^2-4xy+y^2)/(9x^2-y^2)
That is not an equation (there is no = sign). It is just an expression. So, let's see what we have after we factor things a bit:
(3x-y)(x-y) / (3x-y)(3x+y)
(x-y)/(3x+y)