x+2y = 4 এবং xy = 2 হয় , তবে x = কত?
Solution
Correct Answer: Option D
দেওয়া আছে
x + 2y = 4...............(1)
আবার
xy = 2
y = 2/x
y এর মান (1) নং এ বসিয়ে পাই,
x + 2y = 4
⇒ x + (2/x) . 2 = 4
⇒ x + 4/x = 4
⇒ (x2 + 4)/x = 4
⇒ x2 + 4 = 4x
⇒ x2 - 4x + 4 = 0
⇒ x2 - 2.x.2 + 22 = 0
⇒ (x - 2)2 = 0
⇒ x - 2 = 0
⇒ x = 2
x + 2y = 4...............(1)
আবার
xy = 2
y = 2/x
y এর মান (1) নং এ বসিয়ে পাই,
x + 2y = 4
⇒ x + (2/x) . 2 = 4
⇒ x + 4/x = 4
⇒ (x2 + 4)/x = 4
⇒ x2 + 4 = 4x
⇒ x2 - 4x + 4 = 0
⇒ x2 - 2.x.2 + 22 = 0
⇒ (x - 2)2 = 0
⇒ x - 2 = 0
⇒ x = 2
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