Question

How do you solve the system of equations `14x + 18y = - 18` and `- 5x - 9y = 27`?

Answer 1

x=9
y=-8

Explanation:

Elimination method would be best to use here. Multiply the second equation by 2, it becomes -10x-18y=54. Now add this to the first equation 14x +18y =-18. Y term would thus get eliminated and the result would be

4x= 54-18= 36, giving x=9

Now substitute x=9 in -5x -9y=27. This would give

-45-9y=27 Or, -9y= 45+27= 72
Thus y= 72/(-9)= -8

Answer 2

`x=9`
`y=-8`

Explanation:

`14x+18y=-18`
`-5x-9y=27`

Multiply the second equation by `2`

`14x+18y=-18`
`-10x-18y=54`

and sum member by member:

`14x cancel(+18y) -10x cancel(-18y) =-18+54`

`4x=36`

`x=9`

Now substitute the value of `x` in either equation, e.g. the second one:

`-90-18y=54`

`-18y=144`

`y=-8`