Question

How do you write `f(x)=-3x^2+18x-26` in vertex form?

Answer 1

`y=-3(x-3)^2+1`

Explanation:

For a detailed method (different numbers) see https://socratic.org/s/aDvvq6uD

Set `y=-3(x^2+18/(-3)x)-26`

`y=-3(x+18/(-3xx2))^2+k-26`

but `k+(-3)(18/(-3xx2))^2 = 0 => k-27=0=>k=+27`

giving:

`y=-3(x+18/(-3xx2))^2+1`

`y=-3(x-3)^2+1`