Question:a + b = 6 এবং a - b = 4 হলে ab এর মান কত?
A 4 B 5 C 6 D 7
+ AnswerB
+ Explanation`ab = ((a + b)/2)^2 - ((a - b)/2)^2` `= (6/2)^ - (4/2)^2` `= 3^2 - 2^2 ` `= 9 - 4 = 5`
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