Answer:
[tex]\boxed {\boxed {\sf B. \ 13t^{2} -3+6t}}[/tex]
Step-by-step explanation:
We are given this expression and asked to simplify:
[tex]5t^2-(3-6t-8t^2)[/tex]
First, distribute the -1. Multiply each term in the parentheses by -1 or switch the sign of every term inside the parentheses.
[tex]5t^2+ (-1*3)+(-1*-6t)+(-1*-8t^2)[/tex]
[tex]5t^2+(-3)+(6t)+(8t^2)[/tex]
[tex]5t^2-3+6t+8t^2[/tex]
Next, combine like terms. We see that two terms have a t², so they are like terms. We can add them together.
[tex](5t^2+8t^2)-3+6t[/tex]
[tex]13t^2-3+6t[/tex]
The simplified expression is 13t²-3+6t and Choice B is correct.
