Question

Составьте уравнение прямой, проходящей через точки A(2;7) и B(-1;-2)

Answer 1

Ответ:

$A(2;7)\ \ ,\ \ B(-1;-2)\\\\y=kx+b\\\\A(2;7):\ \ 7=2k+b\\\\B(-1;-2):\ \ -2=-k+b\\\\\left\{\begin{array}{l}2k+b=7\\-k+b=-2\end{array}\right\ \ \left\{\begin{array}{l}b=7-2k\\b=k-2\end{array}\right\ \ \left\{\begin{array}{l}7-2k=k-2\\b=k-2\end{array}\right\ \ \left\{\begin{array}{l}3k=9\\b=k-2\end{array}\right$

$\left\{\begin{array}{l}k=3\\b=3-2\end{array}\right\ \ \left\{\begin{array}{l}k=3\\b=1\end{array}\right\ \ \ \ \Rightarrow \ \ \ \boxed{\ y=3x+1\ }$