Question

How do you solve `2x + y = 7` and `4x - y = 23`?

Answer 1

`x,y=5,-3`

Explanation:

`color(blue)(1) )color(blue)(2x+y=7`

`color(blue)(2))color(blue)(4x-y=23`

We can eliminate `y` from the first equation by `-y` in the second equation

Add both of the equations

`rarr(2x+y=7)+(4x-y=23)`

`rarr6x=30`

`color(green)(rArrx=30/6=5`

Now substitute the value of `x` to the first equation

`rarr2(5)+y=7`

`rarr10+y=7`

`color(green)(rArry=7-10=-3`