neverforgetvivistee
How do i find the excluded value of this denominator?
r^3−r^2−49r+49



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Kira_Yamato
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Let the denominator = 0


Kira_Yamato
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Solve the eqn = 0

neverforgetvivistee
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i learned that we factor it first and equal it to zero

neverforgetvivistee
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how do i solve it? it doesn't have a common factor

cwrw238
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try finding a factor using factor theorem

neverforgetvivistee
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thanks i'll learn that go learn that
i haven't learned that yet

cwrw238
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x7 is worth trying (as last term = 7^)
f(7) = 343  49  343 + 49 = 0
ok so (x7) is a factor
now find any other factors by dividing by x7

cwrw238
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factor theorem if f(x) is divisible by xa then f(a) = 0

cwrw238
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r^2 +6r  7

r7 ) r^3−r^2 −49r+49
r^3 7r^2

6r^2  49r
6r^2  42r

7r + 49

cwrw238
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r^2 +6r  7 = (r+7)(r1)
so factors of f(r) =
(r7)(r+7)(r1)

cwrw238
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so excluded value is value of f(r) when r=7,7 or 1

Kira_Yamato
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Yes

Kira_Yamato
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