IIT-JEE 1986Question 1
All points lying inside the triangle formed by the points $(1,3)$, $(5,0)$ and $(-1,2)$ satisfy
Points and Straight Lines
Solution
Check vertices (linear inequalities hold on the whole triangle iff at the vertices): $3x+2y$ gives $9,15,1\ge0$; $2x-3y-12$ gives $-19,-2,-20\le0$. But $2x+y-13<0$ at $(1,3)$ and $-2x+y<0$ at $(5,0)$. So A and C.