[Maximum mark: 5] Consider the function h(x)=log10(4x2−rx+r−1)h(x) = \log_{10}(4x^2 - rx + r - 1)h(x)=log10(4x2−rx+r−1), where x∈Rx \in \mathbb{R}x∈R. Find the possible values of rrr. [5]