Answer:
x = -3 , y = -3
Explanation:
Solve the following system:
{x - 8 y = 21 | (equation 1)
3 x - 8 y = 15 | (equation 2)
Swap equation 1 with equation 2:
{3 x - 8 y = 15 | (equation 1)
x - 8 y = 21 | (equation 2)
Subtract 1/3 × (equation 1) from equation 2:
{3 x - 8 y = 15 | (equation 1)
0 x - (16 y)/3 = 16 | (equation 2)
Multiply equation 2 by 3/16:
{3 x - 8 y = 15 | (equation 1)
0 x - y = 3 | (equation 2)
Multiply equation 2 by -1:
{3 x - 8 y = 15 | (equation 1)
0 x+y = -3 | (equation 2)
Add 8 × (equation 2) to equation 1:
{3 x+0 y = -9 | (equation 1)
0 x+y = -3 | (equation 2)
Divide equation 1 by 3:
{x+0 y = -3 | (equation 1)
0 x+y = -3 | (equation 2)
Collect results:
Answer: {x = -3 , y = -3