How do you find #abs( -4-9i )#? Precalculus Complex Numbers in Trigonometric Form Complex Number Plane 1 Answer Ratnaker Mehta Jun 30, 2016 #|-4-9i|~=9.85.# Explanation: For a complex no. #z=x+iy,# #|z|=|x+iy|=sqrt(x^2+y^2).# Hence, #|-4-9i|=sqrt(16+81)=sqrt97~=9.85.# Answer link Related questions What is the complex number plane? Which vectors define the complex number plane? What is the modulus of a complex number? How do I graph the complex number #3+4i# in the complex plane? How do I graph the complex number #2-3i# in the complex plane? How do I graph the complex number #-4+2i# in the complex plane? How do I graph the number 3 in the complex number plane? How do I graph the number #4i# in the complex number plane? How do I use graphing in the complex plane to add #2+4i# and #5+3i#? How do I use graphing in the complex plane to subtract #3+4i# from #-2+2i#? See all questions in Complex Number Plane Impact of this question 1916 views around the world You can reuse this answer Creative Commons License