Final answer:
The order (M) of the LTI system's filter based on the given difference equation is 2, and its length (L) is 3.
Step-by-step explanation:
The question asks us to determine the order and length of a filter described by the difference equation y[n] = 2x[n] - 3x[n-1] + 4x[n-2].
The order (M) of the filter reflects the highest delay (or lag) in the sequence of the input signal x[n]. In this case, the highest delay is 2 (from the term x[n-2]), which means the filter's order is M=2. The length (L) of the filter is related to the number of coefficients present in the equation, which are the multipliers of the input signal at different delays. We have three coefficients (2, -3, and 4), so the length of this filter is L=3.