Question

Buna! Vreau si eu ex.21(c,d), va rog mult!

Answer 1

$\left[\begin{array}{ccc}-2&-5&1\\-4&-9&1\\3&5&1\end{array}\right]$
= 18+(-20)+(-15) -(-27)-(-10)-20=18-20-15+27+10-20= 0 
deci la punctul c, A,B,C sunt coliniare.

d) 

$\left[\begin{array}{ccc}-1&5&1\\2&-7&1\\4&-15&1\end{array}\right]$
= 7+20-30+28-15-10= 0
=> sunt coliniare