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The number of solutions of x 3 + 4 x - 1 = 0 in the interval x ∈ - 2,1 is

Correct answer

1

Step-by-step solution

Let, f x = x 3 + 4 x - 1 ∴ f ' x = 3 x 2 + 4 > 0 , ∀ x ∈ R Also, f - 2 = - 17 < 0 & f 1 = 4 > 0 As f x is continuous and increasing, it has exactly one root in the interval - 2,1 .

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