Question

How to solve x+7y=0 2x-8y=20

Answer 1

Solve the following system:
{x + 7 y = 0 | (equation 1)
{2 x - 8 y = 20 | (equation 2)


Swap equation 1 with equation 2:
{2 x - 8 y = 20 | (equation 1)
{x + 7 y = 0 | (equation 2)


Subtract 1/2 × (equation 1) from equation 2:
{2 x - 8 y = 20 | (equation 1)
{0 x+11 y = -10 | (equation 2)

Divide equation 1 by 2:
{x - 4 y = 10 | (equation 1)
{0 x+11 y = -10 | (equation 2)

Divide equation 2 by 11:
{x - 4 y = 10 | (equation 1)
{0 x+y = (-10)/11 | (equation 2)

Add 4 × (equation 2) to equation 1:
{x+0 y = 70/11 | (equation 1)
{0 x+y = -10/11 | (equation 2)
Collect results:
Answer:  {x = 70/11
                {y = -10/11