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When do you use a Vertex Form y=a(x – h)2 + k ? What information do you get from a Vertex Form?

Please tell me

User Ben Thul
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1 Answer

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y = a(x - h)² + k is the vertex form of an equation of a parabola with vertex (h,k)

We get the coordinates of the vertex of parabola from that form: (h, k)

We also know if the parabola goes up or down: a>0 or a<0

We can tell how many roots has the equation:

(a>0 and q>0) or (a<0 and q<0) ⇒ no roots

a≠0 and q=0 ⇒ one root: x₀=p

(a>0 and q<0) or (a<0 and q>0) ⇒ two roots

We can also determine the roots (if they exist):

a(x - h)² + k = 0

a(x - h)² = - k

(x - h)² = - k/a

x - h = √[-k/a] ∨ x - h = - √[-k/a]

x = √[-k/a] + h ∨ x = - √[-k/a] + h

Usually you use this form to find the equation of parabola when you have got given the vertex and some other point from that parabola.

User FireBand
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