If f(x) = 3x² + 5x + 7, then f′(x) is:
- 6x + 5
- 3x + 5
- 6x + 7
- 3x² + 5
Show answer and solution
Correct answer: A. 6x + 5
1. Apply power rule to each term: d/dx (3x²) = 6x; d/dx (5x) = 5; d/dx (7) = 0.
2. Sum: f′(x) = 6x + 5.
_Source: syllabus Maths Ch 13 §13.4 Derivatives of Polynomials_