Ask your own question, for FREE!
Mathematics 8 Online
OpenStudy (anonymous):

Can someone help me for a medal?

OpenStudy (anonymous):

Determine which of the following statements is true concerning the values described in column #1 and column #2. Column #1 Column #2 The x-coordinate of the vertex of the graph of y = −2x2 − 4x + 12 The x-coordinate of the vertex of the graph of y = x2 − 4x + 3

OpenStudy (anonymous):

Options are: A: The value found in column #1 is greater than the value found in column #2. B: The value found in column #1 is less than the value found in column #2. C: The value found in column #1 is equivalent to the value found in column #2. D: The relationship between column #1 and column #2 cannot be determined by the information given.

OpenStudy (ineedhelpfast12):

A

OpenStudy (ineedhelpfast12):

Am I right?

OpenStudy (anonymous):

Lol, so sorry for this delay. I'm not sure if you are correct or not, thats why I'm asking for help.

OpenStudy (ineedhelpfast12):

Should be A

OpenStudy (anonymous):

How do you know?

zepdrix (zepdrix):

With you way you posted it, it's really difficult to determine what is in column 1 and what is in column 2.

zepdrix (zepdrix):

Hannah, why you sideways! >.< Pick yerself up! :D

OpenStudy (ineedhelpfast12):

simplify everything

OpenStudy (anonymous):

Oh, sorry. I'll take a screenshot and post it on here. I' not gonna lie, what you said was actually pretty funny :D

OpenStudy (anonymous):

OpenStudy (anonymous):

I'm not sure how to simplify them. Can you explain how you simplified?

zepdrix (zepdrix):

Oh :) So in order to identify the vertex points, you need these equations in vertex form. That usually requires you to `complete the square`. Does that sound familiar?

OpenStudy (anonymous):

Yeah, it does. It's just that when I was going over the lesson, I found it very difficult to understand.

OpenStudy (anonymous):

y = -2x^2 - 4x + 12 = -2(x^2 + 2x) + 12 = -2(x^2 + 2x + 1) + 12 + 2 = -2(x + 1)^2 + 14 y = x^2 - 4x + 3 = (x^2 - 4x) + 3 = (x^2 - 4x + 4) + 3 - 4 = (x - 2)^2 - 1 The vertex is (-1, 14) in the first; (2, -1) in the second. ANSWER: The value found in column #1 is less than the value found in column #2.

OpenStudy (anonymous):

zepdrix can you confirm if his answer is correct or not?

OpenStudy (anonymous):

It seems correct to me, but you seem to be the smarter then me

zepdrix (zepdrix):

Whut? 0_o I dunno, I'm busy doing a problem, and eating yogurt. It's SO good.

OpenStudy (anonymous):

I love yogurt :D. Also, its fine if your doing another problem. I can wait

zepdrix (zepdrix):

you're* grumble grumble <.<

OpenStudy (anonymous):

Should I just go with Damneny's answer?

OpenStudy (anonymous):

Oops, my bad.

zepdrix (zepdrix):

ya his work looks correct c:

zepdrix (zepdrix):

So you having trouble with this whole `complete the square` business? :o

OpenStudy (anonymous):

Yeah, I do sadly. And thanks for confirming that. I'll give you a fan and him a medal

zepdrix (zepdrix):

So HannahBanana, what you do is like uhhhh... ok ok let's look at the first equation,\[\Large\rm -2x^2+4x+12\]Err no no, let's deal with that in a sec, lemme try to be more general first. We would LIKE to have an equation in this form:\[\Large\rm y=x^2+bx\]To complete the square, we take `half` of the b coefficient, and `square` it. \[\Large\rm \left(\frac{b}{2}\right)^2\]This is the value that completes the square for us. So we'll add it in.\[\Large\rm y=x^2+bx+\left(\frac{b}{2}\right)^2\]But holdddd up! We can't just add something willy nilly like that. We have a couple of options. The one you're probably most familiar with is "adding it to both sides". That's a way to keep it balanced, yah? But we want to try another trick instead, we'll add and subtract the quantity at the same time. That's another way to balance things.\[\Large\rm y=\color{orangered}{x^2+bx+\left(\frac{b}{2}\right)^2}-\left(\frac{b}{2}\right)^2\]I colored this in orange because these first three give us our perfect square trinomial. They will condense down like this:\[\Large\rm y=\color{orangered}{\left(x+\frac{b}{2}\right)^2}-\left(\frac{b}{2}\right)^2\]

zepdrix (zepdrix):

Ok ok, but maybe that's too general, lemme just explain how to do it on your first equation then maybe you'll get the hang of it.

zepdrix (zepdrix):

\[\Large\rm y=-2x^2+4x+12\]There is too much stuff here, we gotta try to get that nice form that I talked about before. We don't care about this +12, let's ignore him for now.\[\Large\rm y=-2x^2+4x\qquad\qquad\qquad+12\]We also don't want anything on our x^2 term. But we need to keep the x's grouped together. So we'll factor a -2 out of each x term.\[\Large\rm y=-2(x^2-2x)\qquad\qquad\qquad+12\]Ok with those steps so far? >.<

zepdrix (zepdrix):

Bananz where you at? D: I see how it isssss

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!