Suppose the larger pump alone can empty the tank in L hours, and the smaller pump can finish the job in S hours, then each hour the large pump empties 1/L portion of the tank, and the small pump empties 1/S per hour
Working together for three hours, they empty the whole tank, which is 100% of it, so 3/L+3/S=100%=1
Larger pump can empty the tank in 4 hours less than the smaller one, so L=S-4
replace L: 3/(S-4)+3/S=1
Make the denominator the same to solve for:
3S/[S(S-4)] +3(S-4)/[S(S-4)]=1
(3S+3S-12)/[S(S-4)]=1
(3S+3S-12)=[S(S-4)]
S^2-10s+12=0
use the quadratic formula to solve for S
S is about 8.6
The answer is not whole hour.
180 degress because a stranight angle equals that
Locate 1 on the x axis. This is the horizontal number line.
Draw a vertical line through 1 on the x axis. Extend this vertical line as far up and down as you can.
Notice how the vertical line crosses the blue curve. Mark this point. Then draw a horizontal line from this point to the y axis. The horizontal line will touch -4 on the y axis. So that means the point (1,-4) is on the curve.
If the input it is x = 1, then the output is y = -4
So that's why the answer is choice A
Answer is C
The x and y hit at (2,-3)
