Definite Integration

Let \(f:[-1,2] \rightarrow[0, \infty)\) be a continuous function such that \(\mathrm{f}(x)=\mathrm{f}(1-x), \forall x \in[-1,2]\)

Let \(\mathrm{R}_1=\int_{-1}^2 x \mathrm{f}(x) \mathrm{d} x\) and \(\mathrm{R}_2\) be the area of the region bounded by \(y=\mathrm{f}(x), x=-1, x=2\) and the \(\mathrm{X}\)-axis, then \(\mathrm{R}_2\) is