Constrained optimization introduction local optimization

FindMinimum[3x^4 - 28x^3 + 84x^2 - 96x + 42, {x, 1.1}]

{5., {x -> 1.}}

Minimize[3x^4 - 28x^3 + 84x^2 - 96x + 42, {x}]

{-22, {x -> 4}}

Plot[3x^4 - 28x^3 + 84x^2 - 96x + 42, {x, 0, 5}]

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