How do you factor #3x^2 - 2x -21#? Algebra Polynomials and Factoring Factoring Completely 1 Answer jk.13 Mar 30, 2018 #(3x+7)(x-3)# Explanation: #3x^2+7x-9x-21# find two integers that ADD to -2, MULTIPLY to -63 (#3*-21#) #3x(x-3)+7(x-3)# factor out common factor #(3x+7)(x-3)# 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 3758 views around the world You can reuse this answer Creative Commons License