Look at the following function:
y=2x2−24x
Determine for which values of x the following is true:
f\left(x\right) < 0
To solve the problem, follow these steps:
- Step 1: Solve the quadratic equation 2x2−24x=0.
- Step 2: Factor the equation as 2x(x−12)=0.
- Step 3: Determine the roots, which are x=0 and x=12.
- Step 4: Analyze the intervals determined by these roots: x<0, 0<x<12, and x>12.
- Step 5: Test each interval to see where f(x)<0.
Now let's work through each step:
Step 1: Solve the equation 2x(x−12)=0. This gives us roots at x=0 and x=12.
Step 2: The quadratic can be negative between the roots, so we consider the interval 0<x<12.
Step 3: Test the sign of 2x(x−12) in each interval:
- Interval (−∞,0): Choose a test point x=−1. The expression is 2(−1)((−1)−12)=2(−1)(−13)=26, which is positive.
- Interval (0,12): Choose a test point x=1. The expression is 2(1)(1−12)=2(1)(−11)=−22, which is negative.
- Interval (12,∞): Choose a test point x=13. The expression is 2(13)(13−12)=2(13)(1)=26, which is positive.
Thus, the quadratic is negative in the interval 0<x<12.
Therefore, the solution to the problem is 0<x<12.