Eric Nicholas K's answer to idununderstandasinglething's Secondary 3 E Maths Singapore question.
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Important tricks.
For xy to be as small as possible, we must choose, if we can, one positive number and one negative number. This is because their product is a negative number and all negative numbers are smaller than all non-negative numbers. Within the list of negative numbers, we find one with the largest magnitude (value without the negative sign) so that the number is as small as possible.
For x2 - y2 to be largest, we pick x to be as large a magnitude as possible and y to be as close to 0 as possible.
For xy to be as small as possible, we must choose, if we can, one positive number and one negative number. This is because their product is a negative number and all negative numbers are smaller than all non-negative numbers. Within the list of negative numbers, we find one with the largest magnitude (value without the negative sign) so that the number is as small as possible.
For x2 - y2 to be largest, we pick x to be as large a magnitude as possible and y to be as close to 0 as possible.
Date Posted:
4 years ago
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