Use Crout factorization for tridiagonal systems to solve the following linear systems.
a. x1 − x2 = 0,
−2x1 + 4x2 − 2x3 = −1,
− x2 + 2x3 = 1.5.
b. 3x1 + x2 = −1,
2x1 + 4x2 + x3 = 7,
2x2 + 5x3 = 9.
c. 2x1 − x2 = 3,
−x1 + 2x2 − x3 = −3,
− x2 + 2x3 = 1.
d. 0.5x1 + 0.25x2 = 0.35,
0.35x1 + 0.8x2 + 0.4x3 = 0.77,
0.25x2 + x3 + 0.5x4 = −0.5,
x3 − 2x4 = −2.25.