Question

Qual a equação da reta que passa por A (1,2) e B (3 -1) ?

Answer 1

$Resolu\c{c}\~ao\to \left\{\begin{array}{ccc}m= \frac{\Delta y}{\Delta x} = \frac{-1-2}{3-1} = -\frac{3}{2} \\\\y-y_p = m*(x-x_p)\\\\y - 2 = - \frac{3}{2}*(x-1)\\\\2y-4 = -3x+3\\\\3x+2y-4-3=0\\\\\boxed{\boxed{3x+2y-7=0}} \end{array}\right$

Espero ter ajudado. :))

Answer 2

a =   -1-2  ==> a = - 3
         3 -1                 2

Y = ax + b

2 = - 3(1) + b
         2
4 = - 3 + 2b ==> 2b = 4+ 3 ==> 2b = 7 ==> b = 7/2

Y = - 3x + 7
         2     2