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Identify the open intervals on which the function is increasing or decreasing. $$ f(x)=x^{2}-6 x+8 $$

Short Answer

Expert verified
The function \(f(x) = x^{2} - 6x + 8\) is decreasing for \(x < 3\) and increasing for \(x > 3\).

Step by step solution

01

Find the Derivative

The derivative of the function \(f(x) = x^{2} - 6x + 8\) is given by \(f'(x) = 2x - 6\).
02

Set the Derivative Equal to Zero

Setting the derivative equal to zero gives \(2x - 6 = 0\). Solving for \(x\), we have \(x = 3\).
03

Determine the Sign of the Derivative

We analyze the behavior of the derivative in the intervals determined by the critical point \(x = 3\). Left of 3 (say \(x = 0\)), we see that \(f'(x) = -6 < 0\). So, the function is decreasing for \(x < 3\). Right of 3 (say \(x = 4\)), we have \(f'(x) = 2 > 0\). So, the function is increasing for \(x > 3\).

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