x² + 13x + 42
Ask what two factors when multiplied gives the product of 42 and gives the sum of 13. The factors are 6 and 7.
x² + 7x + 6x + 42
x(x + 7) + 6(x + 7)
(x + 6)(x + 7)
-- - - - - - - - - - - - -s-
2007-01-29 03:03:42
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answer #1
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answered by SAMUEL D 7
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You don't need an example, you simply need to make things work by trying a solution:
if I try to put x in place of the 1st question mark, it gives:
(x + 6)(x + ?) = x^2 + 6x + x? + 6?, ok ?
then by inspecting the result, it's simple to see that what gives 42 as the last term is 7, if I want 6? to be 42. So:
(x + 6)(x + 7) = x^2 + 6x + 7x + (6)(7) = x^2 + 13x + 42
2007-01-29 01:12:28
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answer #2
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answered by Anonymous
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x^2+13x+42
= x^2+ 6x+7x+42
= x(x+6)+7(x+6)
=(x+6)(x+7)
2007-01-29 01:34:35
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answer #3
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answered by Pradeep Chelani 2
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To factor x^2+13x+42
remember F.O.I.L. (First, Outside, Inside Last)
(x+ )(x+ ) We have the x's that are squared, now all that is needed is two numbers that will sum to 13 and will multiply to 42.
7 and 6
(x+7)(x+6)
(The equal sign confused me. It is not an equation, it is an expression.)
2007-01-29 01:24:06
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answer #4
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answered by J C 5
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x+7
The most general way is to use the quadratic formula and find the two roots of the quadratic equation. Lets say they are r1 and r2. Then the equation can be factored as --
(x - r1)(x - r2)
In this case the two roots are -6, -7 so the factorization will be
(x+6)(x+7)
2007-01-29 01:13:12
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answer #5
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answered by newlex 2
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This is an example of a quadratic equation, so if your book has an index, you can try looking that up.
The answer is (x+7). If your book doesn't cover it, there are some online tutorials listed at the site below.
2007-01-29 01:07:29
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answer #6
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answered by funkysmama 2
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x^2+13x+42=(x+6)(x+7)
Perharps you should read up about factorisation.
http://en.wikipedia.org/wiki/Factorisation
2007-01-29 01:41:20
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answer #7
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answered by alfie 1
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x + 7
Do this
(x + ) (x + )
Okay the sum of the numbers has to be 13 and the product has to be 42.
13 , 1 no doesn't work
6,7 yes it works.
Those are the only numbers.
2007-01-29 01:06:54
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answer #8
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answered by trichbopper 4
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(x + 7)(x + 6)
.......
2007-01-29 01:07:21
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answer #9
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answered by Mike M 1
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