9514 1404 393
Answer:
(x, y) = (-1, -16) or (3, 0)
Step-by-step explanation:
Perhaps you want to solve the system of equations ...
- y = x^2 +2x -15
- y -4x = -12
Substituting the first expression for y into the second equation gives ...
x^2 +2x -15 -4x = -12
x^2 -2x -3 = 0 . . . . . . . . add 12
(x -3)(x +1) = 0 . . . . . . . factor
Solutions are the values of x that make the factors zero: x = 3, x = -1.
The corresponding values of y are ...
y = -12 +4x
y = -12 +4{-1, 3} = -12 +{-4, 12} = {-16, 0}
The solutions to the system are ...
(x, y) = (-1, -16) or (3, 0)
For the answer to the question above, the easiest way to determine is changing every runner's speed into the same unit.
<span>First = 10 m/s </span>
<span>Second = 10 miles/min = 16090.34 / 60 m/s (As 1 mile = 1609.34 meter and 1 min = 60 sec) </span>
<span>Second = 260.82 m/s </span>
<span>Third = 10 cm/hr = 10*(0.01)/60*60 (As 1 cm = 0.01 m and 1 hr = 60*60 sec) </span>
<span>Third = 0.000028 m/s </span>
<span>Fourth = 10 km/sec = 10*1000 m/s (As 1 km = 1000 m and time is already in sec) </span>
<span>Fourth = 10000 m/s </span>
<span>So fastest would be the one who covers the largest distance in 1 sec. It would be the fourth one.</span>