Express y=-2x^2+28x-26 in factored form, y=-9x^2+72+81 in ve  TOPIC_SOLVED

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Express y=-2x^2+28x-26 in factored form, y=-9x^2+72+81 in ve  TOPIC_SOLVED

Postby buddy on Sat Mar 07, 2009 9:57 pm

3. Express y= -2x^2 + 28x-26 in factored form
6. Express y= -9x^2 + 72x +81 in vertex form

help plz!!! :shock:
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Postby stapel_eliz on Sat Mar 07, 2009 11:16 pm

Where are you stuck? Which part is causing you difficulty?

buddy wrote:3. Express y= -2x^2 + 28x-26 in factored form

What factor is common between -2, 28, and -26? (Yes, take the "minus" sign, too; it'll make the rest easier.)

Then factor the remaining quadratic. Hint: What factors of 13 add up to -14? :wink:

buddy wrote:6. Express y= -9x^2 + 72x +81 in vertex form

To put this into "y = a(x - h)2 + k" form, you'll need to complete the square.

If you get stuck, please reply showing all your steps. Thank you! :D
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Re: Express y=-2x^2+28x-26 in factored form, y=-9x^2+72+81 in ve

Postby buddy on Wed Mar 11, 2009 12:03 pm

3. -2 is the common factor? so i get -2(x^2+14-13), but i cant factor this?
4. -9(x^2+72x)+81 but i dont knoe what to do next?
:shock: :confused:
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Re: Express y=-2x^2+28x-26 in factored form, y=-9x^2+72+81 in ve

Postby stapel_eliz on Thu Mar 12, 2009 3:09 am

buddy wrote:3. -2 is the common factor? so i get -2(x^2+14-13), but i cant factor this?

Try slowing down and doing your steps more explicitly when you factor. Inside the parentheses, you've dropped an "x" and have lost track of some signs! :oops:

. . . . .-2x2 = -2(x2)
. . . . .28x = -2(-14x)
. . . . .-26 = -2(13)

So what should you get, when you take a -2 out of -2x2 + 28x - 26? :wink:

buddy wrote:4. -9(x^2+72x)+81 but i dont knoe what to do next?

First, check your factorization. It doesn't look like you took the -9 out of the 72x in the middle...?
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Re: Express y=-2x^2+28x-26 in factored form, y=-9x^2+72+81 in ve

Postby buddy on Wed Mar 18, 2009 3:03 pm

i figured t out thnx
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