One form of a quadratic function is given. Fill - in the missing forms

Question

scarlettfarra2000 · Answer

they give you;
Standard Form:
Vertex Form: 
Factored Form:$$y=(x+5)(x-3)$$

scarlettfarra2000 · Answer

For Standard Form this is what I'm thinking $$x ^{2}-3x+5x-15$$

anonymous · Answer

combine like terms in the middle l

anonymous · Answer

it is not in standard form until you combine $-3x+5x$

scarlettfarra2000 · Answer

so$$x ^{2}+12x-15? $$

anonymous · Answer

no

anonymous · Answer

$$5-3\neq 12$$ so $$5x-3x\neq 12x$$

scarlettfarra2000 · Answer

$$x ^{2}+2x-15$$ sorry I thought the 3 was -3 because -3+5=12 I didn't look close enough to see that it was mins

anonymous · Answer

yes that is right

scarlettfarra2000 · Answer

Okay, so how would I start doing the Vertex Form? I have no clue where it start

anonymous · Answer

vertex form looks like $$y=a(x-h)^2+k$$ where the vertex is $(h,k)$ so easiest if you find the vertex first

anonymous · Answer

$a$ is the leading coefficient, in your case it is 1, so you don't have to worry about that

anonymous · Answer

you got $$y=x ^{2}+2x-15$$which is in the form $$y=ax^2+bx+c$$ with $$a=1,b=2,c=-15$$first coordinate of the vertex is always $-\frac{b}{2a}$
compute that first