Solve (Gauss Elimination):
3x1 – x2 + x3 = 2,
- 15x1 + 6x2 – 5x3 = 5,
x1 – 2x2 + 2x3 = 1
Soln:
Or, 3x1 – x2 + x3 = 2 …(i)
Or, - 15x1 + 6x2 – 5x3 = 5 …(ii)
Or, 5x1 – 2x2 + 2x3 = 1 …(iii),
Multiplying equation (i) by 5 and adding with (ii),
Or, x2 = 15 ….(iv)
Multiplying equation (i) by 5 and (iii) by 3 and subtracting (iii) from (i),
Or, x2 + x3 = 7….(v)
Now, we have three equations,
Or, 3x1 – x2 + x3 = 2 …(i)
Or, x2 = 15 …(iv)
Or, x2 – x3 = 7 …(v)
From (iv), we have, x2 = 15.
Using x2 = 15 in (v), we have, x3 = 8.
Using x2 = 15, x3 = 8 in equation (i), we have, x1 = 3.
So, x1 = 3, x2 = 15, x3 = 8.