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neverforgetvivistee

  • 4 years ago

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

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  1. Kira_Yamato
    • 4 years ago
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    Let the denominator = 0

  2. neverforgetvivistee
    • 4 years ago
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    how?

  3. Kira_Yamato
    • 4 years ago
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    Solve the eqn = 0

  4. neverforgetvivistee
    • 4 years ago
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    i learned that we factor it first and equal it to zero

  5. neverforgetvivistee
    • 4 years ago
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    how do i solve it? it doesn't have a common factor

  6. cwrw238
    • 4 years ago
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    try finding a factor using factor theorem

  7. neverforgetvivistee
    • 4 years ago
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    thanks i'll learn that go learn that i haven't learned that yet

  8. cwrw238
    • 4 years ago
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    x-7 is worth trying (as last term = 7^) f(7) = 343 - 49 - 343 + 49 = 0 ok so (x-7) is a factor now find any other factors by dividing by x-7

  9. cwrw238
    • 4 years ago
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    factor theorem if f(x) is divisible by x-a then f(a) = 0

  10. cwrw238
    • 4 years ago
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    r^2 +6r - 7 ---------------- r-7 ) r^3−r^2 −49r+49 r^3 -7r^2 -------- 6r^2 - 49r 6r^2 - 42r --------- -7r + 49

  11. cwrw238
    • 4 years ago
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    r^2 +6r - 7 = (r+7)(r-1) so factors of f(r) = (r-7)(r+7)(r-1)

  12. cwrw238
    • 4 years ago
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    so excluded value is value of f(r) when r=7,-7 or 1

  13. Kira_Yamato
    • 4 years ago
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    Yes

  14. Kira_Yamato
    • 4 years ago
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