Solve for x:
x^4-17 x^2+16 = 0
Substitute y = x^2:
y^2-17 y+16 = 0
The left hand side factors into a product with two terms:
(y-16) (y-1) = 0
Split into two equations:
y-16 = 0 or y-1 = 0
Add 16 to both sides:
y = 16 or y-1 = 0
Substitute back for y = x^2:
x^2 = 16 or y-1 = 0
Take the square root of both sides:
x = 4 or x = -4 or y-1 = 0
Add 1 to both sides:
x = 4 or x = -4 or y = 1
Substitute back for y = x^2:
x = 4 or x = -4 or x^2 = 1
Take the square root of both sides:
Answer: | x = 4 or x = -4 or x = 1 or x = -1
