Answer :

Sure, let's find [tex]\( f(x) \)[/tex] given the derivative [tex]\( f'(x) = 2x^3 - \varphi \)[/tex].

### Step-by-Step Solution:

1. Understand the Problem: We need to find [tex]\( f(x) \)[/tex] given its derivative. The derivative [tex]\( f'(x) \)[/tex] tells us how the function [tex]\( f(x) \)[/tex] changes with respect to [tex]\( x \)[/tex].

2. Given Derivative Expression:
[tex]\[ f'(x) = 2x^3 - \varphi \][/tex]

3. Integrate the Derivative: To find [tex]\( f(x) \)[/tex], we need to find the antiderivative of [tex]\( f'(x) \)[/tex]. This means integrating the expression [tex]\( 2x^3 - \varphi \)[/tex] with respect to [tex]\( x \)[/tex].

4. Set Up the Integral:
[tex]\[ f(x) = \int (2x^3 - \varphi) \, dx \][/tex]

5. Compute the Integral:

- Integral of [tex]\( 2x^3 \)[/tex]:
[tex]\[ \int 2x^3 \, dx = \frac{2}{4} x^4 = \frac{1}{2} x^4 \][/tex]

- Integral of [tex]\( \varphi \)[/tex]:
[tex]\[ \int -\varphi \, dx = -\varphi x \][/tex]

6. Combine the Results:
[tex]\[ f(x) = \frac{1}{2} x^4 - \varphi x + C \][/tex]

Here, [tex]\( C \)[/tex] is the constant of integration, which represents any constant value that could be added to [tex]\( f(x) \)[/tex] since the derivative of a constant is zero.

### Final Function:

Combining all parts together, we get:
[tex]\[ f(x) = \frac{1}{2} x^4 - \varphi x + C \][/tex]

In this function, [tex]\( \varphi \)[/tex] is treated as a constant with respect to [tex]\( x \)[/tex].