Question

begin{array}{l} 4x^1 - 3x^2 + 2x^3 - x^4 = 8 \ 3x^1 - 2x^2 + x^3 - 3x^4 = 7 \ 2x^1 - x^2 quad quad ; - 5x^4 = 6 \ 5x^1 - 3x^2 + x^3 - 8x^4 = 1 \ end{array}