Final answer:
The expression 1 + tan² x can be simplified to sec² x.
Step-by-step explanation:
To simplify the expression 1 + tan² x, we can use the identity tan²x = sec² x - 1.
So, substituting this into the expression, we get:
1 + tan² x
= 1 + (sec² x - 1)
= sec² x
Therefore, the simplified form of 1 + tan² x is sec² x.