The Lagrangian,
has critical points where its partial derivatives vanish:
tells us 
, so that
Then with 
, we get
and 
tells us
Then there are two critical points, 
. The critical point with the negative 
-coordinates gives the maximum value, 
.
Your answer would be B and C
The equation of the straight line is y=mx+q where q is the number on the y-axis where the line passes, as you can see it is -3. It turns into:
y=mx+(-3) -> y=mx-3
Then consider a point on the line and take the coordinates, such as the point with coordinates (-2;-4), so now you know that:
x=-2 and y=-4
At this point you put these values into the equation:
y=mx-3
-4=m(-2)-3
then solve:
-4=-2m-3
-2m=+3-4
-2m=-1
m=+1/2
Put the value of m into the equation and you found it:
y=1/2x-3
We need numbers to help us solve it
