Can you explain me how this is solved in this way.
f(x, y) = x + 2y + 3.
if x = 3 and y = 1 then f(x, y) = 3 + 2 + 3 = 8. We write f(3, 1) = 8.
I just want to know why x=3 and y=1
HOW ARE THEY SOLVED ?
Hello SmallManNo reason - this is just an example, that's all. $\displaystyle f(3,1) = 8$.
You might equally well say, when $\displaystyle x = 2$ and $\displaystyle y = 0, f(x,y) = 2+0+3=5$. So $\displaystyle f(2,0) = 5$.
It's just showing you how to use the function notation when it's a function of two variables.
Grandad
Hi SmallMan,
What is the context of your function? This looks like a min/max function in linear programming. x and y would be determined by the vertices of the feasible region. Is that what this is?
It looks a though x = 3 and y = 1 were given to you up front, and you just substituted them into the function. Can you elaborate a little more?