Question

Determine the vertex form of g(x) = x2 + 2x – 1

Answer 1

`The\ vertex\ form:f(x)=a(x-h)^2+k\\\\g(x)=x^2+2x-1=\underbrace{x^2+2x\cdot1+1^2}_(use\ (*))-1^2-1\\\\\boxed{f(x)=(x+1)^2-2}\\\\(*)\ (a+b)^2=a^2+2ab+b^2`