Let l be a line segment from a (1,0) to B (- 1,2), then the curve integral ∫ L (x + y) ds

Let l be a line segment from a (1,0) to B (- 1,2), then the curve integral ∫ L (x + y) ds

The equation of line AB is
y=1-x
That is x + y = 1
So ∫ L (x + y) ds = ∫ L 1ds = ∫ l DS = | ab | = √ [(- 1-1) ^ 2 + (2-0) ^ 2] = 2 √ 2