# Thread: did i do this parabola question right?..

1. ## did i do this parabola question right?..

i don't know if i did this right...

sketch 2x^2 +12x -14 and indicate all its vertex and intercepts

my vertex tht i got is (-3,-26)

my y-intercept is (0,-14) x-intercept (-1,0) and (7,0)
is this right?

2. Hi there.

One method of finding the minimum of the graph is to convert it to turning point form by completing the square:

$\displaystyle y=2x^2-12x-14$

$\displaystyle y=2(x^2+6x-7)$

$\displaystyle y=2((x+3)^2-16)$

$\displaystyle y=2(x+3)^2-32$

You can now see that the minimum is at $\displaystyle (-3,-32)$

Now to find the x-intercepts let $\displaystyle y=0$

$\displaystyle 2(x+3)^2-32=0$

$\displaystyle (x+3)^2-16=0$

$\displaystyle (x+7)(x-1)=0$

Therefore the x-axis intercepts are at $\displaystyle (-7,0)$ and $\displaystyle (1,0)$

The y-intercept occurs where $\displaystyle x=0$ which is at $\displaystyle (0,-14)$

You should post your working so we can see where you went wrong.