How do you solve x^2+5x+4<=0x2+5x+40?

1 Answer
Jun 26, 2016

x in [-4, -1]x[4,1]

Explanation:

x^2+5x+4 = (x+4)(x+1)x2+5x+4=(x+4)(x+1)

This is zero when x=-4x=4 or x=-1x=1

The quadratic has a positive leading coefficient, so is is an upright parabola, crossing the xx axis at (-4, 0)(4,0) and (-1, 0)(1,0).

Hence any x in [-4, -1]x[4,1] satisfies the required inequality and any value of xx outside that closed interval does not.

graph{x^2+5x+4 [-10, 10, -5, 5]}