Question

If |x| < 1 and y = 1 + x + x² + x³ + ….., then write the value of dy/dx.

Answer 1

As |x| < 1

And y = 1 + x + x² +……. (this is an infinite G.P with common ratio x)

∵ |x| < 1

∴ using the formula for sum of infinite G.P, we have–