Which system of equations has only one solution? 4 x + 2 y = 8. negative 4 x minus 2 y = 3. negative 5 x + y = 6. 5 x minus y = negative 6. negative 3 x + 4 y = 2. 3 x minus 4 y = 0. 2 x + 4 y = 6. 3 x minus 4 y = 9.

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.