Question

Using suitable identities evaluate the following:
(93)^2
(12.5)^2-(7.5)^2
93*109​

Answer 1

93² can be written as (100-7)²

we can use the identity (a-b)² = a² - 2ab + b²

= 100² - 2(100)(7) + 7²

= 10000 - 1400 + 49

= 8600+49

= 8649

(12.5)² - (7.5)²

we can use identity a² - b² = (a+b)(a-b)

= (12.5+7.5)(12.5-7.5)

= (20)(5)

= 400

93 × 109

= (100-7)(100+9)

we can use (x+a)(x+b) = x² + x(a+b) + ab

= 100² + 100(-7+9) +(-7)×9

= 10000 + 200 - 63

= 10137

hope it helps

have a great day

Answer 2

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