Question 614444
The best way to see what's going on is to say
{{{ A = 1 }}}
{{{ B = 1 }}}
{{{ C = 1 }}}
Now change A, B, and C to +3, 0, -3 while others stay +1
I will show plots:
This is The equation to start with:
{{{ graph( 400, 400, -5, 5, -5, 5, x ) }}}
This is A being changed:
{{{ graph( 400, 400, -5, 5, -5, 5, 3*( x - 1 ) + 1, 1, -3*( x - 1 ) + 1 ) }}}
This is B being changed:
{{{ graph( 400, 400, -5, 5, -5, 5, x - 2, x + 1, x + 4 ) }}}
This is C being changed:
{{{ graph( 400, 400, -5, 5, -5, 5, x + 2, x - 1, x - 4 ) }}}
As you can see, 
Changing A affects the slope and shifts right for positive A, left for negative A
Changing B shifts the line right for positive B, left for negative B 
Changing C shifts the line left for positive C, right for negative C