Problem:
If m>0 and the points (m,3) and (1,m) lie on a line with slope m, then m=
Answer Choices:
A. 1
B. 2
C. 3
D. 2
E. 5
Solution:
Since the slope of the line through points (x1,y1) and (x2,y2) is x2−x1y2−y1, it follows that m=1−mm−3. Therefore, m−m2=m−3. Since m>0, it follows that m=3.