Question

determine o valor de k para que os pontos a (1,3)b ( 3,-5) c (-2,k) sejam colineares

Answer 1

$A= \left[\begin{array}{ccc}1&3&1\\3&-5&1\\-2&k&1\end{array}\right] \\ \textup{para ser colineare o determinante igual zero}\\ detA=-5-6+3k-(10+k+9)= -5-6+3k-10-k-9=0 \\ 2k-30=0=\ \textgreater \ k=30/2= 15$