Simplify the expression
[tex]\mleft(8u^2+3u-4\mright)+\mleft(8u^2+3u-1\mright)-\mleft(3u^2-3u-8\mright)[/tex]Removing all the parentheses, taking special care to change the signs of the last three terms:
[tex]8u^2+3u-4+8u^2+3u-1-3u^2+3u+8[/tex]Now collect like terms:
[tex]8u^2+8u^2-3u^2+3u+3u+3u-4-1+8[/tex][tex]13u^2+9u+3[/tex]