Problem

Find the roots of the function f(x)=x39x2+23x15 using the factor theorem.

Answer

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Answer

Therefore, the factors of f(x) are (x1)(x3)(x5), and the roots of the function are x=1, x=3, and x=5.

Steps

Step 1 :The factor theorem states that a polynomial f(x) has a factor (xk) if and only if f(k)=0. So we first need to find a value of x that makes f(x)=0.

Step 2 :By trying a few values, we find that f(1)=13912+23115=0, so (x1) is a factor of f(x).

Step 3 :Next, we can perform polynomial division to divide f(x) by (x1) to find the other factors. The result is x28x+15, which can be factored into (x3)(x5).

Step 4 :Therefore, the factors of f(x) are (x1)(x3)(x5), and the roots of the function are x=1, x=3, and x=5.

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