Question

$If|x|<1then\frac{d}{dx}(1-2x+3x^2-........)=$

• A. $\frac{-2}{(1+x{)}^3}$
• B. $\frac{2}{(1-x{)}^2}$
• C. $\frac{-3}{(1+x{)}^4}$
• D. $\frac{2}{(1+x{)}^3}$

Answer 1

The correct option is A

$\frac{-2}{(1+x{)}^3}$

$1-2x+3x^2-.....=(1+x{)}^{-2}\therefore \frac{dy}{dx}=\frac{-2}{(1+x{)}^3}$