two numbers that multiply to 12 and add up to -8
-6 and -2
(x-6)(x-2)
x= 6 or 2
2007-01-30 01:49:36
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answer #1
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answered by 7
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The simplest way to find the roots (if you can't do it visually as demonstrated above) is to use the formula
a is the coefficient of the x²
b is the coefficient of the x
c is the number with no x
x = (-b ± â(b² - 4ac))/2a
In your example
a = 1
b = -8 (note: negative 8 as you're subtracting not adding 8x)
c = 12
x = (-(-8) ± â((-8)² - 4(1)(12)))/2(1)
= (8 ± â(64 - 48))/2
= (8 ± â16)/2
= (8 ± 4)/2
The ± means you now need to split it into two equations
x = (8 + 4)/2 = 12/2 = 6
x = (8 - 4)/2 = 4/2 = 2
So your answer is x = {2, 6}
2007-01-30 09:56:29
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answer #2
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answered by Tom :: Athier than Thou 6
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x^2 - 8x + 12 = 0
You need two numbers which add up to -8, and multiply to give you + 12. These numbers are - 6 and - 2.
Factorize to get:
(x - 6) (x - 2) = 0
The answer is the negative of the two values above, 6 and 2. Don't forget that there are always 2 answers in this type of quadratic equation.
Therefore, x = 6 or x = 2
2007-01-30 09:50:28
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answer #3
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answered by Ian M 2
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First: multiply the 1st & 3rd coefficient to get "12." Find two numbers that give you "12" when multiplied & "-8" (2nd/middle coefficient) when added/subtracted. The numbers are "-6 & -2"
Sec: rewrite the expression with the new middle coefficients...
x^2 - 6x - 2x + 12 = 0
Third: factor - when you have 4 terms, group "like" terms....
(x^2 - 6x) - (2x + 12) = 0
x(x - 6) - 2(x - 6) = 0
(x - 6)(x - 2) = 0
Fourth: solve the x-variables - set both parenthesis to "0"...
a. x - 6 = 0
*Add "6" to both sides to isolate "x" on one side...
x - 6 + 6 = 0 + 6
x = 6
b. x - 2 = 0
*Add "2" to both sides...
x - 2 + 2 = 0 + 2
x = 2
Solution: 2 and 6
2007-01-30 12:01:33
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answer #4
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answered by ♪♥Annie♥♪ 6
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Quadratic Formula
x = - b ± âb² - 4ac / 2a
x² - 8x + 12
a = 1
b = - 8
c = 12
- - - - - - - - -
x = - (- 8) ± â(- 8)² - 4(1)(12) / 2(1)
x = 8 ± â64 - 48 / 2
x = 8 ± â16 / 2
x = (8 ± 4) / 2
- - - - - - -
Solving for +
x = 8 + 4 / 2
x = 12 / 2
x = 6
The answer is x = 6
- - - - - - - -
solving for -
x = 8 - 4 / 2
x = 4 / 2
x = 2
The answer is x = 2
- - - - - - - - - -s-
2007-01-30 11:01:44
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answer #5
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answered by SAMUEL D 7
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x^2 - 8x + 12 = 0
(x - 6)(x - 2) = 0
x - 6 = 0 or x - 2 = 0
x = 6 or x = 2
QED
2007-01-30 11:28:11
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answer #6
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answered by CSUFGrad2006 5
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factorize
(x-6)(x-2)=0
x-6=0 x-2=0
x=6 x=2
x={2,6}
2007-01-30 11:45:08
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answer #7
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answered by nano_1992_fun 2
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