simultaneous equations

For this we can use the elimination method.

5x + 2y = -2

3x – 5y = 17.4

 

Multiply the top equation through by \(\frac52\) .

\(\frac{25}{2} \) – 5y = -2

 

Now line this up with the second equation and add straight down.

    \(\frac{25}{2} \)x    +    5y = -5

+   3x      –    5y = 17.4

     15.5x +    0y = 12.4

 

15.5x = 12.4

x = 12.4/15.5

x = 0.8

 

Now just use this value for x in either equation to find y.

5(0.8) + 2y = -2

4 + 2y = -2

2y = -6

y = -3