simplify (7t^2+9)+(6t^2+8)

To simplify the expression, we combine like terms.

(7t^2 + 9) + (6t^2 + 8)

We add the coefficients of the like terms:

7t^2 + 6t^2 = 13t^2

We add the constants:

9 + 8 = 17

Therefore, the simplified expression is 13t^2 + 17.