 Hello and welcome to the session. My name is Mansi and I am going to help you with the following question. The question says, find the derivative of 99x at x equal to 100. Before starting with the solution, let us see the key idea behind the question. That is, the theorem 7 of your book that says that let fx be equal to an x raise to power n plus an minus 1 x raise to power n minus 1 and so on till a1x plus a0 be a polynomial function where ai's are all real numbers and an is not equal to 0, then derivative function is given by dfx by dx is equal to n into an x raise to power n minus 1 plus n minus 1 an minus 1 x raise to power n minus 2 and so on till 2 a2x plus a1. So this is our key idea to the question. Using this theorem we find out the solution to this question. So let us see the solution now. First of all, let fx be equal to 99x. Now we have to find dfx by dx that will be equal to 99 because 99 is a constant so it comes down as it is. Now derivative with respect to x of x is 1 because we know that derivative with respect to x of x raise to power n is equal to n into x raise to power n minus 1. In this case n is equal to 1. So x raise to power n minus 1 that is 1 minus 1 becomes 0 and anything raise to power 0 is 1. So dfx by dx equals to 99. We have to find out dfx by dx at the point x equal to 100 since there is no x so this will remain as it is. So our answer to this question is 99. I hope that you understood the question and enjoyed the session. Have a good day.