Question

составьте уравнение прямой, проходящей через данные точки: A(2; -15) и B(-1; 18).

Answer 1

$\mathtt{y=kx+b}\\\boxed{\mathtt{ \left \{ {{-15=2k+b} \atop {18=-k+b}} \right. }}\\\boxed{\mathtt{ \left \{ {{3=k+2b} \atop {x=b-18}} \right. }}\\\boxed{\mathtt{ \left \{ {{3=b-18+2b} \atop {k=b-18}} \right. }}\\\boxed{\mathtt{ \left \{ {{3b=21} \atop {k=b-18}} \right. }}\\\boxed{\mathtt{ \left \{ {{b=7} \atop {k=-11}} \right. }}\\\mathbf{y=-11x+7}$

Answer 2

y=kx+b
-15=2k+b
18=-k+b
отнимем
-33=3k
k=-33:3
k=-11
18=11+b
b=18-11
b=7
y=-11x+7