Question

Solve 2x + y = 7
x – y = –4

Answer 1

Add the first and second equations. The result will be a linear equation in x; solve that equation. Take the solution for x, substitute to get the value for y.

Answer 2

x=1,y=5

Answer 3

Thanks guys.

Answer 4

\[(2x + y = 7)+( x – y = –4) \implies x=1 \implies (x,y)=(1,5)\]The first bit of notation isn't a thing of beauty, but I think you can get the idea.