Find all values of $x$ such that $x^2 - 5x + 4 = 0 $. If you find more than one value, then list your solutions, separated by commas.
x^2 - 5x + 4 = 0
x^2 - x + 4 - 4x = 0
x(x-1) - 4(x-1) = 0
(x-4)(x-1)=0
x=4, x=1
+1678 
