F(-10)=-2, f(-8)=5, and f is continuous. All these mean that f(x) is 0 for x in between -10 and -8.
That is, f at -10 is negative, then at -8 is positive. So the graph of f "cuts" the x-axis for an x value in (-10, -8).
Since there is only one value such that f(x)=0, x can only be -9.
Answer: -9
That is, f at -10 is negative, then at -8 is positive. So the graph of f "cuts" the x-axis for an x value in (-10, -8).
Since there is only one value such that f(x)=0, x can only be -9.
Answer: -9