To simplify this expression, we need to distribute the negative sign in front of the second parentheses.
(12a - 6a^2 + 5) - (2a - 3a^2)= 12a - 6a^2 + 5 - 2a + 3a^2= 12a - 6a^2 + 5 - 2a + 3a^2= 10a - 3a^2 + 5
Therefore, the simplified expression is 10a - 3a^2 + 5.
To simplify this expression, we need to distribute the negative sign in front of the second parentheses.
(12a - 6a^2 + 5) - (2a - 3a^2)
= 12a - 6a^2 + 5 - 2a + 3a^2
= 12a - 6a^2 + 5 - 2a + 3a^2
= 10a - 3a^2 + 5
Therefore, the simplified expression is 10a - 3a^2 + 5.