‌g(x)=√x+1 ‌‌ fog ‌(x)=x+3−√x ‌=(√x+1)2−3(√x+1)+5 ‌=g2(x)−3g(x)+5 ‌⇒f(x)=x2−3x+5 ‌∴f(0)=5 But, if we consider the domain of the composite function fog (x) then in that case f(0) will be not defined as g(x) cannot be equal to zero.