The expression is simplified to give -3√10 + 3√15
Surds refer to mathematical expressions containing square roots (√) or other roots (∛, ∜, etc.) that cannot be simplified to rational numbers. In simpler terms, they involve square roots of numbers that aren't perfect squares.
These expressions cannot be simplified to whole numbers or fractions because their square roots are irrational numbers (non-repeating and non-terminating decimals) and are not perfect squares.
From the information given, we have that;
3√10 + 7√15 - 6√10 - 4√15
collect the like terms, we have;
3√10 - 6√10 + 7√15- 4√15
subtract or add the like terms, we have;
-3√10 + 3√15