How do you solve (x + 8)^2 = 81? Algebra Quadratic Equations and Functions Comparing Methods for Solving Quadratics 1 Answer Alan P. Feb 27, 2016 x=1 or x=-17 Explanation: (x+8)^2= 81 = (+-9)^2 rArr (x+8) = +-9 If (x+8)=+9 then color(white)("XXX")x=+9-8=7 If (x+8)=-9 then color(white)("XXX")x=-9-8=-17 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 2303 views around the world You can reuse this answer Creative Commons License