find the axis of symmetry for this parabola y=-5x^2-10x-13

Question

anonymous · Answer

write the answer as an equation

irishboy123 · Answer

complete the square
$y=-5x^2-10x-13$
might be easier to do it starting with this
$y=-5[x^2+2x+\frac{13}{5}]$

anonymous · Answer

-1?

irishboy123 · Answer

$\large \checkmark$

anonymous · Answer

It's not that

irishboy123 · Answer

it is x = -1 if you copied the question correctly

anonymous · Answer

I copied the question right but -1 wasn't the answer

anonymous · Answer

try this one y=-x^2+6x-8

loser66 · Answer

@Kaelyn78  you want us do your homework, don't you?

irishboy123 · Answer

you could do that one in your head!

anonymous · Answer

these are practice problems, not homework

anonymous · Answer

this paper is not graded

anonymous · Answer

and no I can't, I don't know how to find the axis of symmetry in my head

irishboy123 · Answer

we still haven't finished the first one

if the answer is not x = -1, what is it?!

anonymous · Answer

I don't know, that's why I posted it here.

anonymous · Answer

1 or -1

loser66 · Answer

The first one, @IrishBoy123  showed you all the steps + proof. You said it is not the right answer without any reason. I am with him and don't get why you go to other one without finish the first one. :)

irishboy123 · Answer

do it another way
$y=-5x^2-10x-13$
$y' = -10 x - 10$
$y' = 0 \implies x = -1$

anonymous · Answer

because I entered that answer into the computer and it said it isn't right

astrophysics · Answer

Irish boy is right!

anonymous · Answer

Computers don't lie, and they don't give you an explanation of why it's wrong

anonymous · Answer

I came to the same conclusion he had, I agree with him, but the computer doesn't.

astrophysics · Answer

You can check another way by finding the vertex, $$x= -\frac{ b }{ 2a }$$

astrophysics · Answer

$$x = - \frac{ (-10) }{ 2(-5) } = -1$$

anonymous · Answer

Guys they don't give you an option to do the problem a second time. I entered the answer and it was wrong so I just have to move on to the next question. Proving it to me over and over again will not change anything.

anonymous · Answer

If you ever meet the developers of the program I'm working with you can argue with them about that. Thank you all for your help on that problem.

irishboy123 · Answer

put each new question in a new thread and let's see if we can sort out that pesky computer of yours.  perhaps you should wire it to a lie detector :p

astrophysics · Answer

lool

anonymous · Answer

That would be great... Technology is great when it works, horrible when it doesn't