Let f(x)=(x+5)(x-2)f(x)=(x+5)(x−2)
Now, we can do a sign chart
color(white)(aaaa)aaaaxxcolor(white)(aaaa)aaaa-oo−∞color(white)(aaaa)aaaa-5−5color(white)(aaaa)aaaa22color(white)(aaaa)aaaa+oo+∞
color(white)(aaaa)aaaax+5x+5color(white)(aaaaa)aaaaa-−color(white)(aaaa)aaaa++color(white)(aaaa)aaaa++
color(white)(aaaa)aaaax-2x−2color(white)(aaaaa)aaaaa-−color(white)(aaaa)aaaa-−color(white)(aaaa)aaaa++
color(white)(aaaa)aaaaf(x)f(x)color(white)(aaaaaa)aaaaaa++color(white)(aaaa)aaaa-−color(white)(aaaa)aaaa++
Therefore,
f(x)>=0f(x)≥0, when x in ] -oo,-5 ] uu [2, +oo[x∈]−∞,−5]∪[2,+∞[
graph{(x+5)(x-2) [-28.86, 28.85, -14.43, 14.43]}