Question

A line with gradient of -3,passes through points 3.k and k.8 find the value of k and hence express the equation of the line in the form of ax+by=c ,where a,b and c are constants

Answer 1

Standard way to write points:
(3,k) and (k,8)

we know (8-k)/(k-3) = -3
8 - k = -3k + 9
2k = 1
k = 1/2

equation using m = -3, point is (3, 1/2)
y - 1/2 = -3(x - 3)
times 2
2y - 1 = -6(x-3)
2y - 1 = -6x + 18
6x + 2y = 19