\( 3 a ^ { x } , - 3 a ^ { y } , - 5 a \)

Did you know that expressions like \( 3 a^{x} \), \( -3 a^{y} \), and \( -5 a \) can be combined using the laws of exponents? For example, if \( x \) and \( y \) are constants, and both refer to powers of the same base \( a \), you can add or subtract them in terms of \( a^{x} \) and \( a^{y} \) where applicable. This leads to neat simplifications in algebraic expressions! When dealing with such expressions, a common mistake is overlooking the signs when combining terms. For example, remember that \( -3 a^{y} \) has a negative sign, which affects the final result when you combine it with the positives. Always keep track of those pesky signs, as they can turn a simple addition into a subtraction!