Answer:
[tex]\textsf{A)} \quad 5u^3-2u^2+5u+8[/tex]
Step-by-step explanation:
Given expression:
[tex](-2u^3+5u-1)+(7u^3-2u^2+9)[/tex]
Remove parentheses:
[tex]\implies -2u^3+5u-1+7u^3-2u^2+9[/tex]
Collect like terms:
[tex]\implies -2u^3+7u^3-2u^2+5u-1+9[/tex]
Combine like terms:
[tex]\implies 5u^3-2u^2+5u+8[/tex]
