Given the rational function f(x)=(x−1)(x+2), find the range of f(x).
Therefore, the range of f(x) is all real numbers except f(−2).
Step 1 :The range of a rational function f(x)=p(x)q(x) is the set of all real numbers except the value a such that q(a)=0.
Step 2 :In the given function f(x)=(x−1)(x+2), the denominator is x+2, so x+2≠0, which implies that x≠−2.
Step 3 :Substituting x=−2 in f(x), we get f(−2)=(−2−1)(−2+2)=−30, which is undefined.
Step 4 :Therefore, the range of f(x) is all real numbers except f(−2).