Respuesta :
Here are some more examples:
Let's find the vertex of the parabola given by the function:f(x) = x2 - 4x + 7.To complete the square we look at the middle term's coefficient.b = -4To make a perfect square we find (b/2)2.(-4/2)2 = 4We add 4 to the first two terms and subtract 4 from the constant term.f(x) = x2 - 4x + 4 + 7 - 4 = x2 - 4x + 4 + 3.We rewrite the expression as a perfect square.x2 - 4x + 4 = (x - 2)2 which is (x + b/2)2.We substitute the perfect square into the function.f(x) = (x - 2)2 + 3.According to the standard form of a quadratic function the vertex is (2,3).