[tex] \large\underline \bold{{SOLUTION}}[/tex]
» Expand the binomials
[tex]\longmapsto\rm{x(2x-1)(x+2)=168}[/tex]
[tex]\longmapsto\rm{(2x²-x)(x+2)=168}[/tex]
[tex]\longmapsto\rm{2x³+4x²-x²-2x=168}[/tex]
[tex]\longmapsto\rm{2x³+3x²-2x=168}[/tex]
[tex]\longmapsto\rm{2x³+3x²-2x-168=0}[/tex]
» Factor the polynomial to get the roots
[tex]\longmapsto\rm{(x-4)(2x²+11x+42)=0}[/tex]
[tex]\longmapsto\rm{x-4=0 , \boxed{\sf{x=4}}}[/tex]
[tex] \large\underline{ \bold{ANSWER}}[/tex]
