C-11-Q069mediumsingle_mcqab=cd\dfrac{a}{b}=\dfrac{c}{d}ba=dc হলে ac+bdac−bd=?\dfrac{ac+bd}{ac-bd} = ?ac−bdac+bd=?aa2+b2a2−b2\dfrac{a^2+b^2}{a^2-b^2}a2−b2a