I read about regression in machine learning and came across this gradient descent algorithm to find the minimum value of a cost function. Then I read wikipedia to know more and it says the following
But then I started thinking of what I learnt in my high school math like the one described here in these Khan Academy lectures. The way to take derivative and second derivative test to find maximum and minimum. Then I started wondering why we need iterative gradient descent algorithm when we have the above mentioned high school math method.
I am not sure if I have understood things wrongly.
Can you help me understand why we need gradient descent here ?