Question

O valor de x para que os pontos A(-2, -1), B(0, 3) e C(x, 7) sejam colineares?

a) -2
b) 2
c) 3
d) -3
e) 1

Answer 1

Resposta:

Letra B$\left|\begin{array}{cccc}-2&0&x&-2\\-1&3&7&-1\end{array}\right|_{+} ^{-} = ~0\\\\|-2.3+0.7+x.(-1)-(-1).0-3.x-7.(-2)|=0\\\\|-6-x-3x+14|=0\\\\|-4x+8|=0\\\\-4x+8=0\\\\-4x=-8\\\4x=8\\\\x=\frac{8}{4} \\\\x=2$

Explicação passo-a-passo: