To evaluate the expression [tex]\( x^2 - 1 \)[/tex] when [tex]\( x = 3 \)[/tex], follow these steps:
1. Substitute the value of [tex]\( x \)[/tex] into the expression:
[tex]\[ x = 3 \][/tex]
So, we substitute 3 for [tex]\( x \)[/tex] in the expression [tex]\( x^2 - 1 \)[/tex].
2. Calculate [tex]\( x^2 \)[/tex]:
[tex]\[ x^2 = 3^2 = 9 \][/tex]
This gives us the square of 3, which is 9.
3. Subtract 1 from the result:
[tex]\[ 9 - 1 = 8 \][/tex]
So, the value of the expression [tex]\( x^2 - 1 \)[/tex] when [tex]\( x = 3 \)[/tex] is 8.
Therefore, the correct choice is:
D. 8
