How do you multiply #(7+sqrt(5b))(7–sqrt(5b))#? Algebra Radicals and Geometry Connections Multiplication and Division of Radicals 1 Answer Don't Memorise Jun 18, 2015 # = color(blue)(49 - 5b# Explanation: This is of the form : # color(blue)((a+b)(a-b) = a^2 - b^2# So , #(7+sqrt(5b))(7–sqrt(5b)) = 7^2 - sqrt((5b))^2# # = color(blue)(49 - 5b# 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 1403 views around the world You can reuse this answer Creative Commons License