Use the intercept form of the equation of a parabola, y=a(x-p)(x-q).
y=0.01(x+7)(x+3)
Practice makes perfect
We want to write the equation of the parabola that passes through the point (- 2,0.05) and has x-intercepts - 7 and - 3. To do so, we will use the intercept form of a quadratic function.
y=a(x-p)(x-q)
In this form, p and q are the intercepts. Therefore, we can partially write our equation.
y=a(x-(- 7))(x-( - 3))
⇕
y=a(x+7)(x+3)
Finally, since the parabola passes through the point (- 2,0.05), we can substitute - 2 for x and 0.05 for y in our partial equation to solve for a.
