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 2110 views around the world You can reuse this answer Creative Commons License