Answer :

To evaluate the expression [tex]\( t^2 + 8 r t + r^2 \)[/tex] when [tex]\( r = 3 \)[/tex] and [tex]\( t = 11 \)[/tex], follow these steps:

1. Substitute the values of [tex]\( r \)[/tex] and [tex]\( t \)[/tex] into the expression:
[tex]\[ (11)^2 + 8 \cdot (3) \cdot (11) + (3)^2 \][/tex]

2. Calculate [tex]\( t^2 \)[/tex]:
[tex]\[ 11^2 = 121 \][/tex]

3. Calculate [tex]\( 8 r t \)[/tex]:
[tex]\[ 8 \cdot 3 \cdot 11 = 8 \cdot 33 = 264 \][/tex]

4. Calculate [tex]\( r^2 \)[/tex]:
[tex]\[ 3^2 = 9 \][/tex]

5. Add all the results together:
[tex]\[ 121 + 264 + 9 \][/tex]

6. Finally, sum these values:
[tex]\[ 121 + 264 = 385 \][/tex]
[tex]\[ 385 + 9 = 394 \][/tex]

Therefore, the value of the expression [tex]\( t^2 + 8 r t + r^2 \)[/tex] when [tex]\( r = 3 \)[/tex] and [tex]\( t = 11 \)[/tex] is [tex]\( \boxed{394} \)[/tex].