Question

If c does not equal 0 and the slope of the line passing through (-c, 2c) and (4c, a) is 1, what is the expression for a in terms of c?

Answer 1

slope m between two points (x1,y1) (x2,y2) is given by :

m = (y2-y1) / (x2-x1)

in our case
(x1,y1) = (-c,2c)
(x2,y2) = (4c,a)
m = 1

so :

1 = (a-2c) / (4c -(-c))
1 = (a-2c) / (5c)
5c = a - 2c
a = 7c

Answer 2

thank you :)