 Hi, and welcome to the session. I am Deepika here. Let's discuss the question. Find the intervals in which the following function is strictly increasing or decreasing. 6 minus 9x minus x square. We know that a function is strictly increasing on an open interval where its derivative is positive and a function is strictly decreasing on an open interval where its derivative is negative. So let's start the solution. Given function is 6 minus 9x minus x square. Therefore, aft dash x is equal to minus 9 minus 2x. Now, aft dash x is equal to 0 implies x is equal to minus 9 by 2. Hence, x is equal to minus 9 by 2 divides the real line into two disjoint intervals. They are minus infinity to minus 9 by 2 and minus 9 by 2 to infinity. Now, aft dash x greater than 0 implies if minus 9 minus 2x is greater than 0, that is minus 2x is greater than 9 or x is less than minus 9 by 2 or f is strictly increasing in minus infinity to minus 9 by 2. Now, aft dash x less than 0 if minus 9 minus 2x is less than 0, that is minus 2x is less than 9 or x is greater than minus 9 by 2 or f is strictly decreasing in the interval minus 9 by 2 to infinity. Hence, the answer for the above question is function is strictly increasing for x less than minus 9 by 2 and strictly decreasing for x greater than minus 9 by 2. So, this is the answer for the above question. I hope the question is clear to you. Bye and take care.