Question
Question: If \(f(x) = x^{n},\) then the value of \(f(1) - \frac{f'(1)}{1!} + \frac{f''(1)}{2!} - \frac{f'''(1...
If f(x)=xn, then the value of
f(1)−1!f′(1)+2!f′′(1)−3!f′′′(1)+......+n!(−1)nfn(1) is
A
2n
B
2n−1
C
0
D
1
Answer
0
Explanation
Solution
f(x)=xn⇒f(1)=1, f′(x)=nxn−1⇒f′(1)=n
f′′(x)=n(n−1)xn−2⇒f′′(1)=n(n−1) …..
fn(x)=n!⇒fn(1)=n!, ∴f(1)−1!f′(1)+2!f′′(1)......+n!(−1)nfn(1)
=n⥂C0−n⥂C1+n⥂C2−n⥂C3+......+(−1)nn⥂Cn=0.