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1. যদি x+y = 4, x – y = 3হয়, তবে x + 2y = কত?
- A. ½
- B. ½
- C. ½
- D. ½
Answer: Option D
Explanation:
Here, x + y = 4
And, x - y = 3
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So, 2x = 7 [by addition]
or, x = 7/2 = 3.5
So, 3.5 + y = 4 [from first equation]
or, y = 4 - 3.5 = 2.5
Then, x + 2y = 3.5 + 2×0.5 = 3.5 + 1 = 4.5
And, x - y = 3
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
So, 2x = 7 [by addition]
or, x = 7/2 = 3.5
So, 3.5 + y = 4 [from first equation]
or, y = 4 - 3.5 = 2.5
Then, x + 2y = 3.5 + 2×0.5 = 3.5 + 1 = 4.5
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