indirect and direct proportionality

please i need assistance urgently on the following:

 

 

 

a) y = kx         it is direct proprortionality

b) y = -kx       please state indirect or direct proportionality

it is common knowledge that when there is an increase of y1 to y2 there is a corresponding increase from x1 to x2.....this is direct proportionality.

 

the above definition of direct proportionality does is not applicable on the straight lines   as follows

 

 

a) y = -2x + 10

b) y = -3x

c) y = -x + 8

 

 

 

for the function  y =x2 (x squared)

a)  for the domain x equal to zero or greater than zero (and also less than positive infinity) the curve is an increasing function

b) for the domain x equal to zero or greater than zero (also greater than negative infinity) the curve is a decreasing function based on the  quadratic curve y = x2.

 

 

 

please could you confirm everything as stated above.