Find [tex]$f^{\prime}(x)$[/tex] if [tex]$f(x)=\sqrt{x^4-6x^2+8}$[/tex].

A. [tex]\frac{4y^{\prime} \cdot 2x}{\sqrt{2}-6x^3+3}[/tex]

B. [tex]4(x^3-3x)[/tex]

C. None of these



Answer :

Certainly! Let's walk through the steps to differentiate [tex]\( f(x) = \sqrt{x^4 - 6x^2 + 8} \)[/tex].

To find the derivative [tex]\( f'(x) \)[/tex]:

1. Rewrite the Function:

Rewrite [tex]\( f(x) \)[/tex] as [tex]\( (x^4 - 6x^2 + 8)^{1/2} \)[/tex].

2. Apply the Chain Rule:

We'll use the chain rule: if [tex]\( y = g(h(x)) \)[/tex], then [tex]\( y' = g'(h(x)) \cdot h'(x) \)[/tex].

Here, [tex]\( g(u) = u^{1/2} \)[/tex] where [tex]\( u = x^4 - 6x^2 + 8 \)[/tex].

3. Differentiate [tex]\( g(u) \)[/tex]:

[tex]\( g(u) = \sqrt{u} = u^{1/2} \)[/tex].

Hence, [tex]\( g'(u) = \frac{1}{2} u^{-1/2} = \frac{1}{2 \sqrt{u}} \)[/tex].

4. Differentiate [tex]\( u \)[/tex] with respect to [tex]\( x \)[/tex]:

[tex]\( u = x^4 - 6x^2 + 8 \)[/tex]

Differentiating [tex]\( u \)[/tex] with respect to [tex]\( x \)[/tex] gives [tex]\( u' = 4x^3 - 12x \)[/tex].

5. Combine Using the Chain Rule:

Applying the chain rule, we get:

[tex]\[ f'(x) = g'(u) \cdot u' = \frac{1}{2 \sqrt{u}} \cdot (4x^3 - 12x) \][/tex]

6. Substitute Back [tex]\( u = x^4 - 6x^2 + 8 \)[/tex]:

[tex]\[ f'(x) = \frac{1}{2 \sqrt{x^4 - 6x^2 + 8}} \cdot (4x^3 - 12x) \][/tex]

7. Simplify the Expression:

Factor out common terms in the numerator:

[tex]\[ f'(x) = \frac{1}{2 \sqrt{x^4 - 6x^2 + 8}} \cdot 4x(x^2 - 3) \][/tex]

[tex]\[ f'(x) = \frac{4x(x^2 - 3)}{2 \sqrt{x^4 - 6x^2 + 8}} \][/tex]

Simplify further:

[tex]\[ f'(x) = \frac{2x(x^2 - 3)}{\sqrt{x^4 - 6x^2 + 8}} \][/tex]

Therefore, the derivative of the function is:

[tex]\[ f'(x) = \frac{2x(x^2 - 3)}{\sqrt{x^4 - 6x^2 + 8}} \][/tex]

This is the simplified form of the derivative.