99 Percentile Qs Bank for JEE MainMathematicsDeterminants
If f x ,   g x and h x are polynomials of degree 4 and f x g x h x a b c p q r = m x 4 + n x 3 + r x 2 + s x + t be an identity in x ,   then f ''' 0 - f '' 0 g ''' 0 - g '' ( 0 ) h ''' 0 - h '' 0 a b c p q r is
Options
- A2 ( 3 n - r )
- B2 ( 2 n - 3 r )
- C3 ( n - 2 r )
- DNone of these
Correct answer
A. 2 ( 3 n - r )
Step-by-step solution
Given, f x g x h x a b c p q r = m x 4 + n x 3 + r x 2 + s x + t Differentiating both sides with respect to x and determinant along row. ⇒ f ' x g ' x h ' x a b c p q r + f x g x h x 0 0 0 p q r + f x g x h x a b c 0 0 0 = 4 m x 3 + 3 n x 2 + 2 r x + s ⇒ f ' x g ' x h ' x a b c p q r + 0 + 0 = 4 m x 3 + 3 n x 2 + 2 r x + s Differentiating again with respect to x and determinant along row. ⇒ f '' x g '' x h '' x a b c p q r = 12 m x 2 + 6 n x + 2 r