To solve this you must isolate x. First add 1 to both sides
x² - 1 + 1 = 0 + 1
x² = 1
Now you must take the square root of both sides to cancel out the square from the x
√x² = √1
x = 1 and x = -1
When you take the square root of a number you must remember to take both the positive and negative of the number
Hope this helped!
~Just a girl in love with Shawn Mendes
