Question

How to solve the simultaneous equation


3x+7y=26
4x+5y=13

Answer 1

I found:

x=-3

y=5

Explanation: I would multiply the first equation by −4 and the second by 3 and add together the two equations (in columns):

{−12x−28y=−104

{12x+15y=39

0−13y=−65

So: y=65/13=5

Substitute back this value into the first equation:

3x+7⋅5=26

3x=26−35=−9

x=−9/3=−3