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Home Q & A Board Science-Related Homework Help Mathematics
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ikamu19 ikamu19
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11 years ago

Thanks for the answer. But i'm asking for the application of factoring the difference of two squares in real life. Of how can we use this as part of solving problems in life.
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#1
11 years ago
Well, it could make multiplication of numbers "straddling" a 10 something
you could do in your head.  Mult 29x31, 41x39, 101x99.

Squaring a 2 digit number with a 9 in the unit's place is mentally quite easy
if you use the square of a binomial (A-1)²; do you subtraction of the "middle"
term after adding the squares.
wrote...
#2
11 years ago
I've always used this particular trick:
(x + 1)(x - 1) = x² - 1

So, for instance, I know that:
? 25² = 625 ... so 24 * 26 = 624, which is one less.
? 50² = 2,500 ... so 49 * 51 = 2,499
? 500² = 250,000 ... so 499 * 501 = 249,999

Similarly, (x + 2)(x - 2) = x² - 4
? 25² = 625 ... so 23 * 27 = 621, which is four less.
? 50² = 2,500 ... so 48 * 52 = 2,496

Also, 3 either side gives the square minus 9, 4 either side gives the square minus 16, and so on, but in real life I only use the ones shown above.

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