# Thread: Completing the square

1. ## Completing the square

Basically got coursework in due tomorrow (10% of final marks, kinda a homework sheet).

y=x^2+8x+1 <-- Complete the square and find the min point.

(x+4)^2-15=x^2+8x+1

Got: min point (-4,-15)
Just wondering if the x is a minus or not, because its squared (Above).

y=3x+6x+11 <-- Complete the square and find the min point.
And Im not sure how to go about this, because of the 3x.

Cheers! jD.

2. Originally Posted by Backlock
Basically got coursework in due tomorrow (10% of final marks, kinda a homework sheet).

Just wondering if the x is a minus or not, because its squared (Above).

And Im not sure how to go about this, because of the 3x.

Cheers! jD.
$\displaystyle y=(x+4)^2-15$

The vertex is (-4, -15), so the minimum is the y value. Minimum point is the vertex.

In your second one,

$\displaystyle y=3x^2+6x+11$

$\displaystyle y=3(x^2+2x+1)+11-3$

$\displaystyle y=3(x+1)^2+8$

Vertex is at (-1, 8)

3. Thanks alot, I ended up with $\displaystyle (1/3 , 8)$ Saved a me few marks