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​−x1​y2​−y1​​, it follows that m=1−mm−3​. Therefore, m−m2=m−3. Since m>0, it follows that m=3​.