Existence of a Solution in the Open Interval (0, 1) for a Cubic Equation with Real Coefficients
Let a,b,c∈R. Show that there exists x∈(0,1) such that
4ax3+3bx2+2cx=a+b+c.
Show Hint:
Apply the Rolle's Theorem to the function
φ:[0,1]→R,t↦at4+bt3+ct2−(a+b+c)t.