Question

2. Determine o valor de m para que os pontos A(m, 3), B(2, -4) e C( m, -1) sejam colineares:
a) 2
b) 4
c) -2
d) -4
e) nada

Answer 1

$\begin{vmatrix}m&3&1\\2&-4&1\\m&-1&1\end{vmatrix}=0$

$\mathsf{m(-4+1)-3(2-m) +1(-2+4m)=0}\\\mathsf{-3m-6+3m-2+4m=0}\\\mathsf{4m=8}\\\mathsf{m=\dfrac{8}{4}}$

$\boxed{\boxed{\boxed{\mathsf{m=2}}}}$