If any of the roots of a polynomial are increased, then all of the critical points increase.
Root Dragging Theorem
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References
Anderson, B. "Polynomial Root Dragging." Amer. Math. Monthly 100, 864-866, 1993.Referenced on Wolfram|Alpha
Root Dragging TheoremCite this as:
Weisstein, Eric W. "Root Dragging Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RootDraggingTheorem.html