Question

Solve with matrices. 5x -3y = 18 and 2x + 7y = -1

Answer 1

We'll use Cramer's rule for 2 equations:

ax + by = e

cx + dy = f

5x -3y = 18 a=5 b=-3 e=18

2x + 7y = -1 c=2 d=7 f=-1

denominator determinant (dn) = (a * d) - (c * b) = 5 * 7 - (2 * -3) = 41

x = [(e * d) - (f * b)] / dn

[18 * 7 - (-1 * -3)] / 41 =

123 / 41 = 3

y = [(a * f) - (c * e)] / dn

= (5 * -1) -(2 * 18) / 41 =

-41 / 41 = -1

Source:

1728.com/cramer.htm