Taking a Derivative:
The simplest way to understand a derivative is as a formula for finding the slope of a curve. Or, as a formula that tells you the rate of change of a certain function. When you take a function’s derivative, you are finding that function that provides the slope of the first function. Fortunately, calculating a derivative is simple for some functions, although it can get more complicated as we move on.
First, we will take the derivative of a simple polynomial: . The first step is to take any exponent and bring it down, multiplying it times the coefficient. In other words, bring the 2 down from the top and multiply it by the 4. Then reduce the exponent by 1. The final derivative of that term is , or simply .
The second term is . Since the exponent of x is implied to be 1, we can bring that down and multiply, which does not change the coefficient. Reducing the exponent by 1 makes it 0, so the derivative of is just , or the constant 6. Clearly, for any linear term (a coefficient times a variable with an exponent of 1) like 6x, 9x, or -2x, the derivative will simply be that coefficient.
Remember, the original polynomial we were differentiating (taking the derivative of) was . We can go term-by-term, so the final derivative is determined to be 8x + 6. That's it!
Now let's take the derivative of a few more polynomials to make sure we understand the basics:
Polynomial:
Derivative:
Notice that any constant is eliminated, because 13 is the same as , and when the 0 comes down the whole term becomes 0 and disappears)
Polynomial:
Derivative:
Polynomial:
Derivative:
That's all there is to taking the derivative of a polynomial!