Question:
Tick (✓) the correct answer:
(82)2 − (18)2 = ?
(a) 8218
(b) 6418
(c) 6400
(d) 7204
Solution:
(c) 6400
$(82)^{2}-(18)^{2}$ [using the identity (a-b)(a+b)=a2 -b2]
$=(82+18)(82-18)$
$=(100)(64)$
$=6400$
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