Question

determine y para que os pontos A(3,5) B(-3,8) C(4,y) sejam colineares

Answer 1

$\left[\begin{array}{ccc}3&5&1\\-3&8&1\\4&y&1\end{array}\right] =0 \\ \\ 24+20-3y-32-3y+15=0 \\ \\ 27-6y=0 \\ 27=6y \\ y=27/6 \\ y=13,5$