x+y=12এবং x-y=2 হলে xy এর মান কত?

A    35

B    140

C    70

D    144

Solution

Correct Answer: Option A

 

x + y = 12

x = 12 - y

substituting this equation in thesecond given equation gives us 

12 - y -y =2 

2 y = 10

y = 5

substituting y = 5 in any of the given equations give us 

x + 5 = 12 

x = 7 

 

therefore xy = 7 * 5

xy = 35

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