5�ã2x^3-x�ã18xy^2 simplify as much as possible
(5+4�ã2)(3+4�ã10)multiple and simplify as much as possible
Assuming you meant
5√(2x^3)-x√(18xy^2)
that is
5x√(2x) - 3xy√(2x) = (5x-3xy)√(2x)
(5+4√2)(3+4�√10)
= 15 + 12√2 + 20√10 + 16√20
= 15 + 12√2 + 32√5 + 20√10