Question

The roots of the equation $x^3$ + 2$x^2$ + 5x + 2cos x = 0 in [0, 2$\pi$] is

• A. only one root
• B. only two roots
• C. only three roots
• D. None of these

Answer 1

The correct option is D None of these

$f\left(x\right)=x^3+2x^2+5x+2cosx=0in[0,2\pi ]x(x^2+2x+5)=-2cosx$
No.solution