If $\;1-i\;$ is a root of the equation $\;x^{2} +ax + b=0\;$ where $\;a,b \in R\;$ , then find the values of a and b .

Question

$(a)\;2,3\qquad(b)\;0,2\qquad(c)\;-2,2\qquad(d)\;4,-2$