How do you solve x(4-x)(x-6)<=0x(4x)(x6)0?

1 Answer
Nov 19, 2016

The answer is x in [0,4] uu [6,+ oo[x[0,4][6,+[

Explanation:

Let f(x)=x(4-x)(x-6)f(x)=x(4x)(x6)

Let's do a sign chart

color(white)(aaaa)aaaaxxcolor(white)(aaaa)aaaa-oocolor(white)(aaaa)aaaa00color(white)(aaaaa)aaaaa44color(white)(aaaaaa)aaaaaa66color(white)(aaaaaa)aaaaaa+oo+

color(white)(aaaa)aaaaxxcolor(white)(aaaaaaa)aaaaaaa-color(white)(aaaa)aaaa++color(white)(aaaa)aaaa++color(white)(aaaa)aaaa++

color(white)(aaaa)aaaa4-x4xcolor(white)(aaaa)aaaa++color(white)(aaaa)aaaa++color(white)(aaaa)aaaa-color(white)(aaaa)aaaa-

color(white)(aaaa)aaaax-6x6color(white)(aaaa)aaaa-color(white)(aaaa)aaaa-color(white)(aaaa)aaaa-color(white)(aaaa)aaaa++

color(white)(aaaa)aaaaf(x)f(x)color(white)(aaaaa)aaaaa++color(white)(aaaa)aaaa-color(white)(aaaa)aaaa++color(white)(aaaa)aaaa-

For f(x)<=0f(x)0

The solution is x in [0,4] uu [6,+ oo[x[0,4][6,+[
graph{x(4-x)(x-6) [-14.56, 13.9, -8.47, 5.77]}