x-y=10 এবং x3-y3=1900 হলে xy= কত?

A 20
B 30
C 40
D 50

Correct Answer: 30

x - y= 10x3- y3= 1900xy= ? x3−y3=(x − y)3+3xy (x−y)1900=(10)3+3xy.101000+30xy=190030xy= 1900-1000xy=900/30xy=30
Bissoy MCQ

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