Question 938378
(6, −2) and 
(-1, 4) m ={{{(y[1] - y[2])/(x[1] - x[2] )}}} = -6/7
.......
(-8, 4) and 
(-8, 11)  m ={{{(y[1] - y[2])/(x[1] - x[2] )}}} = -7/0 (ouch!), slope is Undefined