use the product (a+b) (a-b)=a2-b2 to evaluate 21×19
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Answered by
7
(20+1) (20-1)
=20² - 1²
=400-1
=399
Hope it helps...
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my ans is correct
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Answered by
0
21^2-19^2
441-361
(441+361)(441-361)
hope it help
wrong
which is correct ans
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