Question

Solve the simultaneous equations
2x + 5y + 11 = 0
3x - y-8= 0​

Answer 1

x = 1
`(12)/(17)`, y = -2
`(15)/(17)`

Explanation:

2x + 5y + 11 = 0 --- Equation 1

3x - y - 8 = 0

15x - 5y - 40 = 0 --- Equation 2

Equations 1+2: 2x + 5y + 11 + 15x - 5y - 40 = 0 + 0

17x - 29 = 0

17x = 29

x = 29 ÷ 17

x = 1
`(12)/(17)`

Substitute x = 1
`(12)/(17)` into Equation 1:

2x + 5y + 11 = 0

2(1
`(12)/(17)`) + 5y + 11 = 0

3
`(7)/(17)` + 5y = -11

5y = -11 - 3
`(7)/(17)`

= -14
`(7)/(17)`

y = -14
`(7)/(17)` ÷ 5

y = -2
`(15)/(17)`