Mathematics
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OpenStudy (inowalst):
The quadratic expressions \(x^2+5x−14\) and \(49-x^2\) share a common binomial factor.
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OpenStudy (yanasidlinskiy):
So, what's the question? Are we supposed to factor it out?
Parth (parthkohli):
They do.
OpenStudy (inowalst):
Yes. @YanaSidlinskiy I need help doing that.
OpenStudy (welshfella):
first take x out of the quadratic function
OpenStudy (inowalst):
But one is negative and one isn't..
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OpenStudy (welshfella):
oh sorry
you can simplify first
(x^2+5x−14x^2
= 5x - 13x^2
= x(5 - 13x)
OpenStudy (welshfella):
there are no common factors here
are you sure you have the question right?
OpenStudy (inowalst):
The 14 isn't supposed to have \(x^2\)
OpenStudy (welshfella):
i suspect thet the quadratic is x^2+5x−14
OpenStudy (welshfella):
right
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OpenStudy (inowalst):
Sorry about that.
OpenStudy (welshfella):
to factor x^2+5x−14 you need to find 2 numbers whose product is -14 and whose sum is
+5
OpenStudy (welshfella):
can you tell me what those 2 numbers sre?
OpenStudy (welshfella):
think of the factors of -14
OpenStudy (inowalst):
Their product has to be -14 but the sum has to be 5?
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OpenStudy (welshfella):
yes
OpenStudy (inowalst):
Hm.. I don't really know, but I know for the -14..
OpenStudy (welshfella):
-14 = -7 * 2 or
-14 = -2 * 7
OpenStudy (welshfella):
which 2 factors add up to +5?
OpenStudy (inowalst):
-2+7
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OpenStudy (welshfella):
right on
so the factors of (x^2+5x−14)
are ( x - 7)(x + 2)
OpenStudy (welshfella):
if you expand this function you'll see it works out to x^2 + 5x - 14
OpenStudy (welshfella):
* oops my bad
its (x + 7)(x - 2)
OpenStudy (inowalst):
Yes. Thank you so much.
OpenStudy (welshfella):
Now you need to factor x^2 - 49
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OpenStudy (inowalst):
Okay.
OpenStudy (welshfella):
can u do that?
OpenStudy (welshfella):
49 - x^2
OpenStudy (inowalst):
(x-7)(x+7) ? I don't know..
OpenStudy (welshfella):
49 - x^2 = (7 - x)(7 + x)
so can you see the common factor?
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OpenStudy (inowalst):
Yes.
OpenStudy (welshfella):
x + 7
OpenStudy (inowalst):
Oh, okay. Thanks a bunch.