Answer:
zeros of f(x) are -4 and -5
Step-by-step explanation:
[tex]f(x)=x^2+9x+20\\\\on\ using\ splitting\ the\ middle\ term\\\\f(x)=x^2+4x+5x+20\\\\f(x)=x(x+4)+5(x+4)\\\\f(x)=(x+5)(x+4)\\\\f(x)=0\\\\implies\ that\\x=-4 \ and x=-5[/tex]
hence, zeros of f(x) are -4 and -5