Question21 A quadratic function has the equation $y=(x+1)^{2}-9$. What is the equation written in standard form?
A $y=x^{2}+x-8$ B $y=2 x^{2}+2 x-9$ c $y=x^{2}+2 x-9$ D $y=x^{2}+2 x-8$

Studdy Solution
Simplify the equation by combining like terms:
$$y = x^2 + 2x + 1 - 9$$
$$y = x^2 + 2x - 8$$
The equation in standard form is:
$$\boxed{y = x^2 + 2x - 8}$$
The correct answer is option D: $y = x^2 + 2x - 8$.