f(x)=−√5−6x−x2 Let f(x)=y ⇒y=−√−(x2+6x−5) ⇒−y=−(x2+6x+9−9−5) ⇒−y=√−{(x+3)2−14} On squaring both sides, y2=14−(x+3)2 (x+3)2=14−y2 ∴x=√14−y2−3 which is defined only when y∈[−√14,√14] But f(x) will give only negative values. Hence, range of f(x)=[−√14,0]