How do you factor 21x^3 - 28x? Algebra Polynomials and Factoring Factoring Completely 1 Answer Nick F. Jul 5, 2016 x = 0 or x = +-(2sqrt3)/3 Explanation: Start by taking out the common factor, 7x 7x(3x^2 - 4) = 0 7x = 0 or 3x^2 - 4 = 0 x = 0 or x^2 = 4/3 x = 0 or x = +-2/sqrt3 x = 0 or x = +-(2sqrt3)/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 1704 views around the world You can reuse this answer Creative Commons License