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1. a +b =11 এবং a-b=7 হলে, ab =?
- A. 16
- B. 16
- C. 16
- D. 16
Answer: Option D
Explanation:
দেওয়া আছে,
a + b = 11 এবং a - b = 7
আমরা জানি,
ab = (a + b/2)2 - - (a - b/2)2
= (11/2)2 - - (7/2)2
= 121/4 - - 49/4
= 121 - 49/4
= 72/4
= 18
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