(x^3+5x^2−9x−45)/(x−3)(x+5).
Х^2(х+5)-9(х+5) =------------------= (х-3)(х+5) (х^2-9)(х+5) =------------= (х-3)(х+5) (х-3)(х+3)(х+5) =----------------=х+3 (х-3)(х+5)