One thing that you may add is that the matrix (I-hB) is exact the iteration matrix we get when we obtain y_{n+1} from y_n, but this should be a well-known result (and it should have appeared in your textbook).
Calculating eigenvalues of a 2-by-2 matrix is almost direct. It is equivalently to solving a quadratic equation (and in this question you don\’t even need to because the square term is already factored out )
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There is no extra steps because the question itself is simple.
If you don’t understand some steps, you may point out specifically where.
