How do you solve 5 - x^2 = 20? Algebra Quadratic Equations and Functions Comparing Methods for Solving Quadratics 1 Answer Dan Kemp Jun 1, 2017 x = -3.873 Explanation: 5-x^2 = 20 -x^2 = 20-5 -x^2 = 15 -x = sqrt15 -x = 3.873 color(blue)(x = -3.873 We can now prove our answer by substituting x for -3.873 5-x^2 = 20 5- -3.873^2 = 20 5 + 3.873^2 = 20 5 + 15 = 20 Answer link Related questions What are the different methods for solving quadratic equations? What would be the best method to solve -3x^2+12x+1=0? How do you solve -4x^2+4x=9? What are the two numbers if the product of two consecutive integers is 72? Which method do you use to solve the quadratic equation 81x^2+1=0? How do you solve -4x^2+4000x=0? How do you solve for x in x^2-6x+4=0? How do you solve x^2-6x-16=0 by factoring? How do you solve by factoring and using the principle of zero products x^2 + 7x + 6 = 0? How do you solve x^2=2x? See all questions in Comparing Methods for Solving Quadratics Impact of this question 2534 views around the world You can reuse this answer Creative Commons License