Dophins
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| Joined: 03 Jan 2012 |
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| 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
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Dophins
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| 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
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| 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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| 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
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| 17 Apr 2016 07:21 AM |
@expol it would be +12 and -5
2x²+12x-5x-30=0
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airwolf12
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| Joined: 02 Mar 2009 |
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| 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
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| 17 Apr 2016 07:22 AM |
@gim
-12 + 5 = -7
-12 x 5 = -60
~ Exᴘᴏʟᴛɪᴏɴ || #GʀᴀɪɴGᴀɴɢ || GFX Dᴇsɪɢɴᴇʀ || R$37,059 || RAP: 883,875 |
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Expoltion
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| 17 Apr 2016 07:23 AM |
oops accidentally made 7 a negative lol
~ Exᴘᴏʟᴛɪᴏɴ || #GʀᴀɪɴGᴀɴɢ || GFX Dᴇsɪɢɴᴇʀ || R$37,059 || RAP: 883,875 |
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Dophins
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| 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
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Tumelar
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| Joined: 14 Mar 2011 |
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| 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
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| 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
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Tumelar
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Alloviser
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| 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
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| 17 Apr 2016 07:43 AM |
What's your coumtry? I'm from Poland :P |
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Alloviser
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Tumelar
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| 17 Apr 2016 07:45 AM |
| We call it "delta". Δ=b^2-4ac |
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Tumelar
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| 17 Apr 2016 07:45 AM |
| Allov, let's form the Commonwealth! :> |
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Alloviser
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| 17 Apr 2016 07:45 AM |
| we call it "diskriminantas" XDD |
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Alloviser
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Tumelar
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| 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
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| 17 Apr 2016 07:49 AM |
But Poland isn't part of Baltic States o_o
Rip |
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