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Re: NEED HELP WITH MATH HOMEWORK

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Dophins is not online. Dophins
Joined: 03 Jan 2012
Total Posts: 25
17 Apr 2016 07:11 AM
Solve the equation 2x²+7x-30=0

Show your working please.

I believe you do 2 x -30 = -60

So -60 is the product and 7 is the sum.

So i need two numbers which add up to make 7 and times together to make -60

Must be integers.


wat wat in the butt
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Dophins is not online. Dophins
Joined: 03 Jan 2012
Total Posts: 25
17 Apr 2016 07:14 AM
bump


wat wat in the butt
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Dophins is not online. Dophins
Joined: 03 Jan 2012
Total Posts: 25
17 Apr 2016 07:18 AM
can nobody do maths?


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GimmeYourDog is not online. GimmeYourDog
Joined: 12 Mar 2013
Total Posts: 8295
17 Apr 2016 07:18 AM
We might be in different Algebra stages but what I'm working on right now is finding the ordered pair to watch the equation
The answer to that is;
(2x + 10)(x - 3)
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Expoltion is not online. Expoltion
Joined: 29 Sep 2013
Total Posts: 15135
17 Apr 2016 07:18 AM
0 = 2x^2 - 7x - 30, 2 x -30 is -60
we need factors of -60 that add up to -7, and -12 x 5 works so we can factor it.

2x^2 - 12x + 5x - 30 = 0
2x(x - 6) + 5(x - 6) = 0
(2x + 5)(x - 6) = 0
x = -5/2 or x = 6


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GimmeYourDog is not online. GimmeYourDog
Joined: 12 Mar 2013
Total Posts: 8295
17 Apr 2016 07:20 AM
But 5 and 6 can't add up to 7?
You would need to use 10 and 3.
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Dophins is not online. Dophins
Joined: 03 Jan 2012
Total Posts: 25
17 Apr 2016 07:21 AM
@expol it would be +12 and -5

2x²+12x-5x-30=0


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airwolf12 is not online. airwolf12
Joined: 02 Mar 2009
Total Posts: 12319
17 Apr 2016 07:22 AM
what does x equal?


no, i won't give 30k for valk. stop. STOP.
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Expoltion is not online. Expoltion
Joined: 29 Sep 2013
Total Posts: 15135
17 Apr 2016 07:22 AM
@gim

-12 + 5 = -7

-12 x 5 = -60


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Expoltion is not online. Expoltion
Joined: 29 Sep 2013
Total Posts: 15135
17 Apr 2016 07:23 AM
oops accidentally made 7 a negative
lol


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Dophins is not online. Dophins
Joined: 03 Jan 2012
Total Posts: 25
17 Apr 2016 07:24 AM
2x²+7x-30=0
2x²=12x-5x-30=0
2x(x+6)-5(x+6)
(x+6)(2x-5)
x=-6 or x=2/-5

That is the answer

Thanks for your responses guys


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Dophins is not online. Dophins
Joined: 03 Jan 2012
Total Posts: 25
17 Apr 2016 07:25 AM
or is it x=-5/2?


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Tumelar is not online. Tumelar
Joined: 14 Mar 2011
Total Posts: 2745
17 Apr 2016 07:33 AM
It's easy.

2x²+7x-30=0

a = 2
b = 7
c = -30

Δ = b^2 - 4*a*c

Δ = (7)^2 - 4*2*(-30)
Δ = 49 - (-240)
Δ = 49 + 240
Δ = 289

√Δ = √289 = 17

x1 = (-b-√Δ)/2a
x2 = (-b+√Δ)/2a

x1 = (-7-17)/2*2 = (-24)/4 = -6
x2 = (-7+17)/2*2 = (10)/4 = 2.5

Am I right?
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:40 AM
2x²+7x-30=0


a=2
b=7
c=-30

D (idk it's called "D" in us country)= b²- 4ac = 49+240 = 289

x1/2 = -b +- 17. x1/2 = -7 +- 17
_______ ______
2a. 4


x1 = -6
x2 = 2.5
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:41 AM
Tumelar was right
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Tumelar is not online. Tumelar
Joined: 14 Mar 2011
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17 Apr 2016 07:42 AM
???
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:43 AM
That's how we do that in our country xd

Atleast answer is correct so yeah
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Tumelar is not online. Tumelar
Joined: 14 Mar 2011
Total Posts: 2745
17 Apr 2016 07:43 AM
What's your coumtry?
I'm from Poland :P
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:44 AM
Lithuania
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Tumelar is not online. Tumelar
Joined: 14 Mar 2011
Total Posts: 2745
17 Apr 2016 07:45 AM
We call it "delta". Δ=b^2-4ac
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Tumelar is not online. Tumelar
Joined: 14 Mar 2011
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17 Apr 2016 07:45 AM
Allov, let's form the Commonwealth! :>
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:45 AM
we call it "diskriminantas" XDD
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:46 AM
And maybeh
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Tumelar is not online. Tumelar
Joined: 14 Mar 2011
Total Posts: 2745
17 Apr 2016 07:47 AM
:>

Dum, dum, dum let's conquer everything from the Baltic Sea to the Black Sea again.
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Alloviser is online. Alloviser
Joined: 21 Mar 2015
Total Posts: 17236
17 Apr 2016 07:49 AM
But Poland isn't part of Baltic States o_o

Rip
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