Mathematics
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OpenStudy (anonymous):
Medals and fans+testimonial!!!
Factor f(x) = x^3 + x^2 – 4x – 4 = 0 completely showing all work.
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OpenStudy (anonymous):
@kewlgeek555
OpenStudy (anonymous):
@ganeshie8
ganeshie8 (ganeshie8):
factor first two terms
factor last two terms
ganeshie8 (ganeshie8):
x^3 + x^2 – 4x – 4
--------- -------
ganeshie8 (ganeshie8):
wats the GCF of first two terms ?
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OpenStudy (anonymous):
x^2 right?
ganeshie8 (ganeshie8):
Yes !!
pull it out
ganeshie8 (ganeshie8):
x^3 + x^2 – 4x – 4
x^2(x + 1) - 4x - 4
-------
ganeshie8 (ganeshie8):
now look at last two terms.
wats the GCF ?
OpenStudy (anonymous):
4
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ganeshie8 (ganeshie8):
yup
ganeshie8 (ganeshie8):
x^3 + x^2 – 4x – 4
x^2(x + 1) - 4x - 4
x^2(x + 1) - 4(x + 1)
---------- --------
ganeshie8 (ganeshie8):
now look at those two groups.
is there anything common ?
ganeshie8 (ganeshie8):
(x + 1) is the common right ?
OpenStudy (anonymous):
yes
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ganeshie8 (ganeshie8):
so u can pull it out
ganeshie8 (ganeshie8):
x^3 + x^2 – 4x – 4
x^2(x + 1) - 4x - 4
x^2(x + 1) - 4(x + 1)
(x+1)(x^2-4)
ganeshie8 (ganeshie8):
are we done ?
or can we still factor it ?
OpenStudy (anonymous):
they both have x
ganeshie8 (ganeshie8):
notice that x^2-4 = x^2-2^2
and use the identity :
a^2-b^2 = (a+b)(a-b)
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ganeshie8 (ganeshie8):
x^3 + x^2 – 4x – 4
x^2(x + 1) - 4x - 4
x^2(x + 1) - 4(x + 1)
(x+1)(x^2-4)
(x+2)(x^2-2^2)
(x+2)(x+2)(x-2)
(x+2)^2(x-2)
ganeshie8 (ganeshie8):
now its completely factored.
see if it makes more or less sense
OpenStudy (anonymous):
thank you, you put it very simply
ganeshie8 (ganeshie8):
glad it mad sense :) u wlc :)
ganeshie8 (ganeshie8):
*made