How do you solve #x^2=21#? Algebra Quadratic Equations and Functions Use Square Roots to Solve Quadratic Equations 1 Answer Marie Feb 26, 2017 #x = +-sqrt(21)# Explanation: To find #x^2# you have to find the square root of #21# #x = +-sqrt(21) ~~+-4.5286# Answer link Related questions Can you use square roots to solve all quadratic equations? How do you use square roots to solve quadratic equations? How do you solve #4x^2-49=0# by taking square roots? How do you solve #(x-3)^2+25=0#? How do you use square roots to solve #2(x+3)^2=8#? What is Newton's formula for projectile motion? How do you solve for x in the equation #(x-3)^2+25=0#? How do you solve the equation #3(x-2)^2-12=0# How do you solve #3x^2+8x=9+2x#? How do you solve #4x^2=52# solve using the square root property? See all questions in Use Square Roots to Solve Quadratic Equations Impact of this question 7931 views around the world You can reuse this answer Creative Commons License