Answer:
see explanation
Explanation:
you are looking for perfect square factors of the numbers under the radical sign. both numbers and the sum are irrational because they contain √5
125 = 5×25
80 = 5×16
3√125 = 3√(25×5) = 3×5√5 = 15√5
√80 = √(16×5) = 4√5
1) 15√5 + 4√5 = 19√5 the √5 is the same square root so you add the coefficients
perfect square factors are bold
4×√(25×2)×√(9×2) =
4×5×3×√(2×2) =
60×√4 =
2) 60 × 2 = 120
the numbers are both irrational but the answer is rational because √2 ×√2 = √4 = 2