in simplest radical form. \[ 7 \sqrt{5}-9 \sqrt{5} \]

To simplify the expression \( 7 \sqrt{5} - 9 \sqrt{5} \), you can combine like terms. Since both terms have the same radical, you can subtract the coefficients: \[ (7 - 9) \sqrt{5} = -2 \sqrt{5}. \] So, the expression in simplest radical form is \(-2 \sqrt{5}\). To visualize this, think of 7 apples and you take away 9 apples. You end up with a deficit of 2 apples, hence the negative sign in front! It’s like borrowing in math, keeping it fun and relatable. This approach also showcases how simplifying expressions with radicals often parallels the simplification with variables or numbers. Just look for those common elements to make things easier for yourself!