Let \( C: x^{2}+y^{2}=4 \) and \( C' : x^{2}+y^{2}-4\lambda x+9=0 \) be two circles. If the set of all values of \( \lambda \) so that the circles \( C \) and \( C' \) intersect at two distinct points, is \( \mathbb{R}-[a,b] \), then the point \( (8a+12,\,16b-20) \) lies on the curve:
