Exercise · ZW-CRITICAL-POINTS-007 · ★★☆ Intermediate
What are the critical points of \(f(x)=x^{4}-8x^{2}\)?
Choose one option.
Show answer
- B. \(x=-2,\ 0,\ 2\)
Explanation
Differentiate: \(f'(x)=4x^{3}-16x=4x(x-2)(x+2)\). The critical points are \(x=-2,\ 0,\ 2\).
Review the concept: Critical points
A critical point of \(f\) is a number \(c\) in the domain where \(f^{\prime}(c)=0\) or \(f^{\prime}(c)\) does not exist. Local maxima and minima of a function at an interior point occur at critical points.
\[f'(c)=0\ \ \text{or}\ \ f'(c)\ \text{does not exist}\]
More practice problems: critical points
- ZW-CRITICAL-POINTS-001 A critical point of f is a number c in the domain where...
- ZW-CRITICAL-POINTS-002 What are the critical points of f(x)=x^3 - 3 x?
- ZW-CRITICAL-POINTS-003 What are the critical points of f(x)=2 x^3 - 9 x^2 + 12 x?
- ZW-CRITICAL-POINTS-004 What are the critical points of f(x)=x^4 - 4 x^3?
- ZW-CRITICAL-POINTS-005 What are the critical points of f(x)=x^3 - 12 x + 5?
- ZW-CRITICAL-POINTS-006 What value of x is a critical point of f(x)=x^2-6x?
- ZW-CRITICAL-POINTS-008 How many critical points does f(x)=x^2/3 have, and which are they?
- ZW-CRITICAL-POINTS-009 If f is differentiable at c, which condition makes c a critical point?