What can you add to x^2-9x to get a perfect square trinomial? Algebra Polynomials and Factoring Factor Polynomials Using Special Products 1 Answer vanessa May 12, 2018 20.25 Explanation: In a perfect square, the equation is ax^2+bx+c, where abs(b) = 2asqrt(c). Therefore, to find c, plug in a and b. abs(b)=2asqrt(c) abs(-9) = 2*1*sqrt(c) 9 = 2*sqrt(c) 4.5 = sqrt(c) 20.25 = c Answer link Related questions How do you factor special products of polynomials? How do you identify special products when factoring? How do you factor x^3 -8? What are the factors of x^3y^6 – 64? How do you know if x^2 + 10x + 25 is a perfect square? How do you write 16x^2 – 48x + 36 as a perfect square trinomial? What is the difference of two squares method of factoring? How do you factor 16x^2-36 using the difference of squares? How do you factor 2x^4y^2-32? How do you factor x^2 - 27? See all questions in Factor Polynomials Using Special Products Impact of this question 4584 views around the world You can reuse this answer Creative Commons License