Question

PLEASE HELP I DONT KNOW WHAT TO DO !! I APPRECIATE IT IF YOU HELP ME !

Answer 1

Answer:

x = ±20

Step-by-step explanation:

x^2 -1=399

Add 1 to each side

x^2 = 399+1

x^2 = 400

Take the square root of each side

sqrt(x^2) = ±sqrt(400)

x = ±20