Step-by-step explanation:
Use the vertex
[tex] - 8 {x}^{2} + 6[/tex]
formula, we know that h is 0 and k is 6 so we get
[tex]a(x {}^{2} ) + 6[/tex]
Now, we set that equal to y and plug in -1 for x and -2 for y to solve for a.
[tex]a( (- 1) {}^{2} ) + 6 = - 2[/tex]
[tex]a(1) + 6 = - 2[/tex]
[tex]a = - 8[/tex]
So our formula is
[tex] - 8( {x}^{2} ) + 6[/tex]
ir
[tex] - 8 {x}^{2} + 6[/tex]