Question

Sabe-se que os pontos A, B e C são alinhados (colineares), tendo coordenadas de A(2,X), B(-2,-5) e C(1,1). Logo, medida X (ordenada) será: [ D] =

Answer 1

$\huge\begin{vmatrix}2&x&1\\-2&-5&1\\1&1&1\end{vmatrix}=0$

$\mathsf{2(-5-1)-x(-2-1)+1(-2+5)=0}\\\mathsf{-12+3x+3=0}\\\mathsf{3x=12-3}\\\mathsf{3x=9}$

$\mathsf{x=\dfrac{9}{3}}\\\huge\boxed{\boxed{\boxed{\mathtt{x=3}}}}$