Determine X for Negative Values of the Function: y=2x²-24x

Question

Look at the following function:

y=2x224x y=2x^2-24x

Determine for which values of x x the following is true:

f\left(x\right) < 0

Step-by-Step Solution

To solve the problem, follow these steps:

  • Step 1: Solve the quadratic equation 2x224x=0 2x^2 - 24x = 0 .
  • Step 2: Factor the equation as 2x(x12)=0 2x(x - 12) = 0 .
  • Step 3: Determine the roots, which are x=0 x = 0 and x=12 x = 12 .
  • Step 4: Analyze the intervals determined by these roots: x<0 x < 0 , 0<x<12 0 < x < 12 , and x>12 x > 12 .
  • Step 5: Test each interval to see where f(x)<0 f(x) < 0 .

Now let's work through each step:

Step 1: Solve the equation 2x(x12)=0 2x(x - 12) = 0 . This gives us roots at x=0 x = 0 and x=12 x = 12 .

Step 2: The quadratic can be negative between the roots, so we consider the interval 0<x<12 0 < x < 12 .

Step 3: Test the sign of 2x(x12) 2x(x - 12) in each interval:

  • Interval (,0) (-\infty, 0) : Choose a test point x=1 x = -1 . The expression is 2(1)((1)12)=2(1)(13)=26 2(-1)((-1) - 12) = 2(-1)(-13) = 26 , which is positive.
  • Interval (0,12) (0, 12) : Choose a test point x=1 x = 1 . The expression is 2(1)(112)=2(1)(11)=22 2(1)(1 - 12) = 2(1)(-11) = -22 , which is negative.
  • Interval (12,) (12, \infty) : Choose a test point x=13 x = 13 . The expression is 2(13)(1312)=2(13)(1)=26 2(13)(13 - 12) = 2(13)(1) = 26 , which is positive.

Thus, the quadratic is negative in the interval 0<x<12 0 < x < 12 .

Therefore, the solution to the problem is 0<x<12 0 < x < 12 .

Answer

0 < x < 12