To find the value of* k*, you need to first **find the gradient of the tangent** of the curve. Then you will **differentiate the equation** of the curve and **equate it to the gradient of the tangent** to **find the x-coordinate**. Next you will **substitute the x coordinate into the equation** of the curve to **find the y coordinate**. Lastly you will **substitute both the x and y coordinates into the linear equation** (straight line equation) and find* k.*

Step 1: Find the gradient of the tangent from the equation of normal.

Step 2: Differentiate the equation of the curve, equate it to the gradient of the tangent to find x.

Step 3: Substitute the *x* value into the equation of the curve to find the y coordinate.

Step 4: Substitute both the *x* and *y* coordinate into the linear equation (straight line equation) to find *k.*

At first sight, the question look very simple. But if you look a little deeper, you realize that it is not that easy to find the x and y coordinates in order to find *k*. This is a typical exam of a O-Level exam question where you need to use formulas and methods from more then one topic to solve a problem. Some question will require knowledge from up to three different topics. So please don’t have a ‘tunnel vision’ and be flexible in using different methods and formulas.