Which values of xxx must be excluded for the expression x+1x2−4x+3\frac{x+1}{x^2 - 4x + 3}x2−4x+3x+1?
x=1x = 1x=1
x=3x = 3x=3
x=−1x = -1x=−1
x=−3x = -3x=−3