Question

I need help please, i never understood system of equations

Answer 1

Given the system of equations;

`\begin{gathered} x+y+z=11..............equation1 \\ \\ y+z=9......................equation2 \\ \\ z=5.............................equation3 \end{gathered}`

Substitute equation 3 in equation 2;

`\begin{gathered} y+z=9 \\ \\ y+5=9 \\ \\ y=9-5 \\ \\ y=4 \end{gathered}`

Substitute equation 3 and the value of y in equation 1;

`\begin{gathered} x+y+z=11 \\ \\ x+4+5=11 \\ \\ x=11-4-5 \\ \\ x=2 \end{gathered}`

ANSWER:

`x=2,y=4,z=5`

CORRECT OPTION: B