How do you simplify #-5sqrt21*-3sqrt42#? Algebra Radicals and Geometry Connections Multiplication and Division of Radicals 1 Answer GiĆ³ Apr 10, 2015 You can write your product as: #[-5sqrt(7*3)]*[-3sqrt(7*6)]=# #=[-5sqrt(7)sqrt(3)]*[-3sqrt(7)sqrt(6)]=# #=[-5sqrt(7)sqrt(3)]*[-3sqrt(7)sqrt(3)sqrt(2)]=# Multiplying: #=15*7*3*sqrt(2)=315sqrt(2)# Answer link Related questions How do you simplify #\frac{2}{\sqrt{3}}#? How do you multiply and divide radicals? How do you rationalize the denominator? What is Multiplication and Division of Radicals? How do you simplify #7/(""^3sqrt(5)#? How do you multiply #(sqrt(a) +sqrt(b))(sqrt(a)-sqrt(b))#? How do you rationalize the denominator for #\frac{2x}{\sqrt{5}x}#? Do you always have to rationalize the denominator? How do you simplify #sqrt(5)sqrt(15)#? How do you simplify #(7sqrt(13) + 2sqrt(6))(2sqrt(3)+3sqrt(6))#? See all questions in Multiplication and Division of Radicals Impact of this question 1220 views around the world You can reuse this answer Creative Commons License