How do you factor #3x²-12xy-63y²#? Algebra Polynomials and Factoring Factoring Completely 1 Answer Alan P. Jun 3, 2015 Given #3x^2-12xy-63y^2# Extract the obvious common numeric factor #3# #color(white)("XXXX")##=3(x^2-4xy-21)# #21# can be factored as #3xx7# and #3-7 = -4# so #color(white)("XXXX")##=3(x+3)(x-7)# Answer link Related questions What is Factoring Completely? How do you know when you have completely factored a polynomial? Which methods of factoring do you use to factor completely? How do you factor completely #2x^2-8#? Which method do you use to factor #3x(x-1)+4(x-1) #? What are the factors of #12x^3+12x^2+3x#? How do you find the two numbers by using the factoring method, if one number is seven more than... How do you factor #12c^2-75# completely? How do you factor #x^6-26x^3-27#? How do you factor #100x^2+180x+81#? See all questions in Factoring Completely Impact of this question 1522 views around the world You can reuse this answer Creative Commons License