Question

evaluate without calculating the actual squares 21 sqaure minus 20 square.
please send it with explanation. fast
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Answer 1

Answer:

(21²–20²)

==> ( 20 + 1 )² – (20)²

by using formula (a+b)² = a²+ b² + 2ab

==> [ (20)² + (1 )² + 2 X 20 X 1 ] – (20)²

==> (20)² + 1 + 40 –(20)²

==> 40 + 1

==> 41

Ans = 41