Steps:
1) Group the like terms and simplify.
2) Do follow the BODMAS Rule. Simplify terms inside the brackets, first. Then, follow this serial: Division, Multiplication, Addition, Subtraction.
Method:
[tex](2u^3 + 6u^2 + 3) + (2u^3 - 7u + 6)[/tex]
= [tex]2u^3 + 6u^2 + 3 + 2u^3 - 7u + 6[/tex]
= [tex]2u^3+2u^3+6u^2-7u+3+6[/tex]
= [tex](2u^3+2u^3)+6u^2-7u+(3+6)[/tex]
= [tex]4u^3+6u^2-7u+9[/tex]
