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If a( a + 2) = 24

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boomgoesthegmat Senior | Next Rank: 100 Posts Default Avatar
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If a( a + 2) = 24

Post Wed May 04, 2016 4:42 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    If a( a + 2) = 24 and b( b + 2) = 24, where a does not equal b, then a + b =

    A) -48
    B) -2
    C) 2
    D) 46
    E) 48

    OA: B

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    Post Wed May 04, 2016 5:42 am
    boomgoesthegmat wrote:
    If a( a + 2) = 24 and b( b + 2) = 24, where a does not equal b, then a + b =

    A) -48
    B) -2
    C) 2
    D) 46
    E) 48

    OA: B
    Given: a(a + 2) = 24
    Expand: a² + 2a = 24
    Rearrange: a² + 2a - 24 = 0
    Factor: (a + 6)(a - 4) = 0
    So, a = -6 OR a = 4

    Given: b(b + 2) = 24
    Expand: b² + 2b = 24
    Rearrange: b² + 2b - 24 = 0
    Factor: (b + 6)(b - 4) = 0
    So, b = -6 OR b = 4

    Since we're told that a ≠ b, we know that one value (a or b) is -6 and the other value is 4
    So, a + b = (-6) + 4 = -2

    Answer: B

    Cheers,
    Brent

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