Q. Which compound inequality represents the value of x?(x−1)(x+1)>0
Find Zeros: Find the zeros of the quadratic by setting each factor to zero.x−1=0 gives x=1.x+1=0 gives x=−1.
Determine Intervals: Determine the intervals to test around the zeros: (−∞,−1), (−1,1), and (1,∞).
Test Around Zeros: Test a value from the interval (−∞,−1), say x=−2.(−2–1)(−2+1)=(−3)(−1)=3, which is positive.
Combine Positive Intervals: Test a value from the interval (−1,1), say x=0.(0−1)(0+1)=(−1)(1)=−1, which is negative.
Combine Positive Intervals: Test a value from the interval (−1,1), say x=0.(0−1)(0+1)=(−1)(1)=−1, which is negative.Test a value from the interval (1,∞), say x=2.(2−1)(2+1)=(1)(3)=3, which is positive.
Combine Positive Intervals: Test a value from the interval (−1,1), say x=0.(0−1)(0+1)=(−1)(1)=−1, which is negative.Test a value from the interval (1,∞), say x=2.(2−1)(2+1)=(1)(3)=3, which is positive.Combine the intervals where the expression is positive. The solution is x < -1 or x > 1.