is the slope always positive if the coordinatesof two points on the line are positive
No.
If you mean that the x and y components of each point are positive, the answer is no.....consider the points (1,6) and (3,4).....the slope between these two points is given by :
[ 4 - 6] / [ 3 - 1 ] = -2 / 2 = -1
NO.
