f(x) = - 2(x -
)² -
the equation of a quadratic in vertex form is
y = a(x - h)² + k
where (h, k ) are the coordinates of the vertex and a is a multiplier
To obtain this form use the method of completing the square
• the coefficient of the x² term must be 1 , factor out - 2
= - 2(x² -
x) - 2
• add / subtract (half the coefficient of the x-term )² to x² -
x
= - 2(x² + 2(-
)x +
-
) - 2
= - 2(x -
)² +
- 2
= - 2(x -
)² -