Algebra Solve an inequality write as an interval

Algebra
Tutor: None Selected Time limit: 1 Day

Solve the inequality

x^3 + 5x^2 >or equal to 4x + 20

Write your answer as an interval or union of intervals.

Please note that the sign is supposed to have a line under it making it 'or equal to.'

Oct 22nd, 2015

Hello!

x^3+5x^2-4x-20>=0.

The left part is

(x-2)(x+2)(x+5)   (I guessed roots from the factors of the free term 20).

It is positive on +infinity and changes sign at each root.

The answer: x in [-5, -2] U [2, +infinity).

Please ask if something is unclear.
Oct 22nd, 2015

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Oct 22nd, 2015
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Oct 22nd, 2015
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