fiendex wrote:
If \(0 \leq x \leq 4\) and \(y < 12\), which of the following CANNOT be the value of xy?
A. -2
B. 0
C. 6
D. 24
E. 48
My approach to solving this is the good old taking it option by option (it isn't as time-consuming as it sounds). Remember, all you need is one case that satisfies xy being equal to one of the options. So try to deliberately pick values that will work and help you eliminate options:
A. Yes, if y=-2 and x=1, this one is possible. Strike off.
B. Yes, if x=0, this one is possible. Strike off.
C. Yes, if x=2, and y=3 or vice versa. Strike off.
D. Yes, if x=4, y=6. Strike off.
E. Hmm. The maximum value y can take is 11; the max x can take is 4. xy= 44. If the maximum values of x and y haven't worked out, no others will.
hence the final answer is E.
Hope that is helpful.
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