f^2+7f+10/f+2

f^2+7f+10/f+2

This is certainly a function of  f. 

Looking for the zeros. 

OK?

ƒ(f) = f² + 7f + 10 / f + 2 = 0        [ * f

f³ + 7f² + 10 + 2f = 0

http://equationsolver.intemodino.com/de/kubische-gleichungen-loesen.html

f = - 6.9198137

Greetings asinus :- ) !