(লিখিত প্রশ্ন) If f(x,y) = (x² - 2xy + y²)/(x² - y²) then f(-x,-y) = ?
A (x - y)/(x + y)
B (x - y)/x
C (x + y)/(x + y)
D কোনটিই নয়
Solution
Correct Answer: Option A
দেওয়া আছে,
f(x,y) = (x² - 2xy + y²)/(x² - y²)
⇒ f(-x, -y) = {(-x)² - 2(-x)(-y) + (-y)²}/{(-x)² - (-y)²}
⇒ f(-x, -y) = (x² - 2xy + y²)/(x² - y²)
= (x - y)²/(x² - y²)
= {(x - y) (x - y)}/{(x - y)(x + y)}
= (x - y)/(x + y)