Questions: Question 21
4 pts
Use the given table for (f(x)=a x^2+b x+c) to solve the inequality (f(x)<0).
x -6 -4 -2 0 2 4 6
f(x) 20 0 -12 -16 -12 0 20
(x<-4) or (x>4)
(x<-5) or (x>5)
(-5<x<5)
(-4<x<4)
Transcript text: Question 21
4 pts
Use the given table for $f(x)=a x^{2}+b x+c$ to solve the inequality $f(x)<0$.
\begin{tabular}{r|rrrrrrr}
x & -6 & -4 & -2 & 0 & 2 & 4 & 6 \\
\hline $\mathrm{f}(\mathrm{x})$ & 20 & 0 & -12 & -16 & -12 & 0 & 20
\end{tabular}
$x<-4$ or $x>4$
$x<-5$ or $x>5$
$-5
Solution
Solution Steps
To solve the inequality \( f(x) < 0 \) using the given table, we need to identify the intervals where the function values are negative. By examining the table, we can see that \( f(x) \) is negative for \( x = -2, 0, 2 \). Therefore, the interval where \( f(x) < 0 \) is between the points where the function changes from positive to negative and back to positive. This corresponds to the interval \(-4 < x < 4\).
Step 1: Identify Function Values
From the given table, we have the function values \( f(x) \) at specific points:
\( f(-6) = 20 \)
\( f(-4) = 0 \)
\( f(-2) = -12 \)
\( f(0) = -16 \)
\( f(2) = -12 \)
\( f(4) = 0 \)
\( f(6) = 20 \)
Step 2: Determine Intervals Where \( f(x) < 0 \)
By analyzing the function values, we find that \( f(x) < 0 \) in the intervals:
Between \( x = -2 \) and \( x = 0 \)
Between \( x = 0 \) and \( x = 2 \)
Step 3: Combine Intervals
The combined interval where \( f(x) < 0 \) is:
\[
(-2, 0) \cup (0, 2)
\]
Final Answer
The solution to the inequality \( f(x) < 0 \) is:
\[
\boxed{-4 < x < 4}
\]