How do you simplify #(3+5i)(2+15i)#? Precalculus Complex Numbers in Trigonometric Form Multiplication of Complex Numbers 1 Answer Kalyanam S. Jul 11, 2018 #color(magenta)(=> -69 + 55i# Explanation: #(3 + 5i) * (2 + 15i)# #=> 3*2 + 3*15i + 2*5i + 5i * 15i#, removing braces. #=> 6 + 45i + 10i + 75i^2#, multiplying term by term. #=> 6 - 75 + 45i + 10i#, regrouping terms as also #i^2 = -1# #=> -69 + 55i# Answer link Related questions How do I multiply complex numbers? How do I multiply complex numbers in polar form? What is the formula for multiplying complex numbers in trigonometric form? How do I use the modulus and argument to square #(1+i)#? What is the geometric interpretation of multiplying two complex numbers? What is the product of #3+2i# and #1+7i#? How do I use DeMoivre's theorem to solve #z^3-1=0#? How do I find the product of two imaginary numbers? How do you simplify #(2+4i)(2-4i)#? How do you multiply #(-2-8i)(6+7i)#? See all questions in Multiplication of Complex Numbers Impact of this question 1844 views around the world You can reuse this answer Creative Commons License