Question

4. Пряма у = kx + l проходить через точки C(1; 8) i D-2; -1). Знайдіть kii. ​

Answer 1

$\displaystyle\bf\\y=kx+l\\\\C(1 \ ; \ 8) \ \ \ \Rightarrow \ \ \ x=1 \ \ ; \ \ y=8\\\\D(-2 \ ; \ -1) \ \ \ \Rightarrow \ \ \ x=1-2\ \ ; \ \ y=-1\\\\\\\left \{ {{8=k+l} \ |\cdot 2\ \atop {-1=-2k+l}} \right. \\\\\\\left \{ {{2k+2l=16} \atop {-2k+l=-1}} \right. \\-----------\\3l=15\\\\l=15:3=5\\\\k=8-l=8-5=3\\\\Otvet: \ l=5 \ \ ; \ \ k=3$