Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

if g = [(r + 2)^3 - 8] / r where r does not = 0, how do you find lim g _ (as r approaches 0)?

1) lim g ( as r approaches 0)

2) lim g ( as r approaches 2)

3)lim g ( as r approaches a)

manythanks!

1 Answer

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  • 1 decade ago
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    [(r + 2)^3 - 8] = (r+2 - 2)((r+2)^2 + 2(r+2) + 4)

    = [r (r^2 + 4r + 4 + 2r + 4 + 4)]

    = r (r^2 + 6r + 12)

    so:

    1) lim g ( as r approaches 0) = lim r (r^2 + 6r + 12) / r

    = lim (r^2 + 6r + 12) = 12

    r --> 0

    2) 2^2 + 6(2) + 12 = 28

    3) sub r with a:

    a^2 + 6a + 12

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