Find the derivation of each of the following from the first principle:
x3 – 2x2 + x + 3
Let f(x) = x3 – 2x2 + x + 3
We need to find the derivative of f(x) i.e. f’(x)
We know that,
…(i)
f(x) = x3 – 2x2 + x + 3
f(x + h) = (x + h)3 – 2(x + h)2 + (x + h) + 3
Putting values in (i), we get
Using the identities:
(a + b)3 = a3 + b3 + 3ab2 + 3a2b
(a + b)2 = a2 + b2 + 2ab
Putting h = 0, we get
f’(x) = (0)2 + 2x(0) + 3x2 – 2(0) – 4x + 1
= 3x2 – 4x + 1
Hence, f’(x) = 3x2 – 4x + 1