Look at the function below:
y=(x−4.4)(x−2.3)
Then determine for which values of x the following is true:
f(x) < 0
To determine when the quadratic function y=(x−4.4)(x−2.3) is negative, we need to analyze the sign of the product across the different intervals defined by its roots.
- Step 1: Identify the roots of the function. The roots occur when each factor equals zero, which are x=2.3 and x=4.4.
- Step 2: Divide the x-axis into intervals based on these roots: x<2.3, 2.3<x<4.4, and x>4.4.
- Step 3: Test a value from each interval:
- For x<2.3, try x=2: y=(2−4.4)(2−2.3)=(−2.4)(−0.3)=0.72, so the product is positive.
- For 2.3<x<4.4, try x=3: y=(3−4.4)(3−2.3)=(−1.4)(0.7)=−0.98, so the product is negative.
- For x>4.4, try x=5: y=(5−4.4)(5−2.3)=(0.6)(2.7)=1.62, so the product is positive.
From this analysis, we see that the quadratic function is negative for values of x in the interval 2.3<x<4.4. This is the range where the function changes sign from positive to negative back to positive.
Therefore, the correct answer is 2.3<x<4.4.