calculus test corrections. 1 question
posted by jonna .
Find the minimum value of f(x, y) = y – x + 1 for the polygonal convex set determined by this system of inequalities.
x > 0 y > 0 2x + y< 4
the answer is 1. please tell me why

Review your material on linear optimization. The max or min value of f(x,y) is found to be at the vertices of the region defined by the constraints.
Here, the region is a triangle, with vertices at (0,0) (2,0) (0,4)
f(0,0) = 1
f(2,0) = 1
f(0,4) = 5