Margie is standing on a bridge looking at the river below. She throws a rock over the bridge with an initial
velocity of 60 ft/sec. If the height, h, of the rock at the rime t seconds after it was thrown can be modeled by the
equation h(t) = −16t

2 + 60t + 72, how long will it take for the rock to reach the surface of the water? Round

to the nearest tenth.

Here we know that Margie is standing on a bridge looking at the river. She throws a rock over the bridge with an initial  velocity of 60 ft/sec. The height, h, of the rock at the rime t seconds after it was thrown can be modeled by the  equation:

To calculate how long will it take for the rock to reach the surface of the water, we need to set . So:

Given that time can't be negative, we just choose the positive value. Therefore, it will take 4.70 seconds for the rock to reach the surface water.

i can answer this question sweetie!

step-by-step explanation:

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3