what is the formula of(a+b)(a-b)?
回答 (28)
2008-12-27 11:41 am
✔ 最佳答案
(a+b)(a-b)=a^2-b^2 answer @(^_^)@
2008-12-27 11:19 am
a^2-b^2
2008-12-28 10:20 am
a^2-b^2
2008-12-27 12:55 pm
Distributing the first term and then the second we have
a(a-b)+b(a-b)
distributing here we obtain
a^2-ab+ba-b^2
Since multiplication is commutative we know that ab and ba are the same so that -ab+ba=0
we are left with
a^2-b^2
(Note that subtraction is NOT commutative, so this is NOT the same as b^2-a^2)
Good luck
a(a-b)+b(a-b)
distributing here we obtain
a^2-ab+ba-b^2
Since multiplication is commutative we know that ab and ba are the same so that -ab+ba=0
we are left with
a^2-b^2
(Note that subtraction is NOT commutative, so this is NOT the same as b^2-a^2)
Good luck
2008-12-27 11:39 am
a^2-b^2
2008-12-27 11:21 am
The square of the first, minus the square of the second:
a^2 - b^2
a^2 - b^2
2008-12-29 6:37 am
(a-b)(a+b)=a(a+b)-b(a+b) = a^2 +a*b - b*a - b^2 = a^2 - b^2
2008-12-28 6:55 am
All the above are good answers. The formula is famous for obtaining results or to evaluate positive variants from negative ones and vice versa. Use, therefore, very thoroughly this formula for easy solutions.
2008-12-27 3:58 pm
a^2 - b^2
2008-12-27 3:27 pm
a^2-b^2
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