The vertex of the graph is (2,-4). It is a minimum as it is the lowest point on the parabola facing upwards. This would be option C.
Solution
A=4πr2=4·π·82≈804.24772
Approximately = 804.25
We call x the 4 points-worth problems and y the 3 points-worth problems
You know that x+y = 32
4x+3y = 111
You know that the difference from the x and y is 32 so write:
x = 32-y
Substitute at x the value of 32-y
4(32-y)+3y = 111
128-4y +3y = 111
-4y+3y = 111-128
-y = -17
y = 17
If you want to check if (1,2) is a solution to the system, you have to plug the x and y values back into both equations. If they work for one equation, but not the other, than the coordinates are not a solution to the system.
3(1) - 4(2) = -5
3 - 8 = -5
-5 = -5
2 = 4(1) - 2
2 = 4 - 2
2 = 2
Since both of these checks are true, then (1,2) is a solution to the system.
