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Thread: Solving

  1. #1
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    Solving

    Solve the following:
    a) 22x-2(2x)=3
    b) a bacterial culture starts with 1500 bacteria. After 5h, the estimated count is 35 000. What is the doubling period?
    c) When the function f(x)=ax3+7x2+bx-8 is divided by (x+1) it has a remainder of 18; and (x-2) is a factor. Determine a and b.
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  2. #2
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    Re: Solving

    (a) let $\displaystyle u = 2^x$ ... can you solve $\displaystyle u^2 - 2u = 3$ ?

    (b) $\displaystyle y = y_0 e^{kt}$

    $\displaystyle 35000 = 1500e^{k \cdot 5}$

    solve for the growth constant $\displaystyle k$, then determine the time $\displaystyle t$ when $\displaystyle y = 3000$

    (c) $\displaystyle f(-1) = 18$ and $\displaystyle f(2) = 0$ ... why?

    you should get two equations with two unknowns ... solve for a and b
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