# Express in form f(x)=a(x-h)^2+k

• Nov 29th 2008, 11:42 AM
ZE2001
Express in form f(x)=a(x-h)^2+k
Express f(x)=-2x^2+4x+1 in the form f(x)=a(x-h)^2+k. Find the vertex and the y-intercept and then graph the function.

I have no idea where to even begin. Anyone?
• Nov 29th 2008, 11:47 AM
Chris L T521
Quote:

Originally Posted by ZE2001
Express f(x)=-2x^2+4x+1 in the form f(x)=a(x-h)^2+k. Find the vertex and the y-intercept and then graph the function.

I have no idea where to even begin. Anyone?

Rewrite it as $-2(x^2-2x)+1$, then complete the square on $-2(x^2-2x)$

Can you try to take it from here?
• Nov 29th 2008, 12:07 PM
ZE2001
Quote:

Originally Posted by Chris L T521
Rewrite it as $-2(x^2-2x)+1$, then complete the square on $-2(x^2-2x)$

Can you try to take it from here?

Okay here's what I came up with:

f(x)=(x-1)^2-3/2
• Nov 29th 2008, 12:11 PM
running-gag
Quote:

Originally Posted by ZE2001
Okay here's what I came up with:

f(x)=(x-1)^2-3/2

Nearly
You just forgot -2 factor
f(x)=-2[(x-1)^2-3/2]
f(x)=-2(x-1)²+3
• Nov 29th 2008, 12:14 PM
ZE2001
Quote:

Originally Posted by running-gag
Nearly
You just forgot -2 factor
f(x)=-2[(x-1)^2-3/2]
f(x)=-2(x-1)²+3

Thank you!