[tex]f(x)=x^2-1\\\\g(x)=x+2\\\\f(g(x))=?\\\\\text{Put x+2 to the f(x)}\\\\f(g(x))=(x+2)^2-1=x^2+2\cdot x\cdot2+2^2-1=x^2+4x+3\\\\Answer:\ f(g(x))=x^2+\boxed{4}x+\boxed{3}[/tex]
