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Question
Evaluate the following using suitable identity:
(998)3
Solution
It is known that,
(a + b)3 = a3 + b3 + 3ab(a + b) and (a − b)3 = a3 − b3 − 3ab(a − b)
∴ (998)3 = (1000 − 2)3
= (1000)3 − (2)3 − 3(1000)(2)(1000 − 2)
= 1000000000 − 8 − 6000(998)
= 1000000000 − 8 − 5988000
= 1000000000 − 5988008
= 994011992
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