My instincts told me if we plug values less than zero, viz -1,-2,-3 we could get the answer quickly
If x = -1 f(x) = -8
If x = -2 f(x) = -9
We can stop at this point since -9 is the lowest value in the choices. The answer is
Choice E.
If we proceed further
if x = -3 f(x) = -8
Note that f(x) decreases in value and increases once again (because it is a parabola). So it will never come back to -9 again. But we can try one more value:
if x = -4 f(x) = -5
So we can be sure -9 is the lowest value. This method required simple mental calculation and is probably faster than the other methods depending on your mental skills.
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