The inequality given is #x(x-1)(x+2)>0# i.e. product of all the terms is positive. It is apparent that sign of terms #(x+2)#, #x# and #(x-1)# will change around the values #-2#, #0# and #1# respectively. In sign chart we divide the real number line using these values, i.e. below #-2#, between #-2# and #0#, between #0# and #1# and above #1# and see how the sign of #x(x-1)(x+2)# changes.
Sign Chart
#color(white)(XXXXXXXXXXX)-2color(white)(XXXXX)0color(white)(XXXXX)1#
#(x+2)color(white)(XXXX)-ive color(white)(XXXX)+ive color(white)(XX)+ive color(white)(XXX)+ive#
#xcolor(white)(XXXXXXX)-ive color(white)(XXXX)-ive color(white)(XX)+ive color(white)(XXX)+ive#
#(x-1)color(white)(XXXX)-ive color(white)(XXXX)-ive color(white)(XX)-ive color(white)(XXX)+ive#
#x(x-1)(x+2)#
#color(white)(XXXXXXXX)-ive color(white)(XXXX)+ive color(white)(XX)-ive color(white)(XXX)+ive#
It is observed that #x(x-1)(x+2)> 0# when either #-2 < x < 0# or #x > 1#, which is the solution for the inequality.