Help please! this ones easy i just dont know how to do it

Duffy was analyzing the trajectory made after throwing a football. his coach was able to measure that his throw reached a maximu

gregori [183]

Answer:

4.35 seconds.

Step-by-step explanation:

Let x represent the time the independent variable and y be dependent variable (height of the ball).

We are told that Duffy figured that the ball left his hand at a height of 5 feet. This means at x equals 0, y was 5 or initial height of ball is 5 feet.

We have been given that Duffy's coach measured that his throw reached a maximum height of 18 feet after 2 seconds. This means that at x equals 2 y was 18.

As point (2,18) represents maximum height of ball, so it will be vertex of parabola.

Since initial height of ball is less than maximum height, so our parabola will be downward opening and leading coefficient will be negative.

We know that vertex form of a downward opening parabola is in form: $y=-a(x-h)^2+k$

$y=-a(x-2)^2+18$

Let us find value of a using point (0,5).

$5=-a(0-2)^2+18$

$5=-a*4+18$

$5-18=-a*4+18-18$

$-13=-4a$

$\frac{-13}{-4}=\frac{-4a}{-4}$

$\frac{13}{4}=a$

Therefore, the equation $y=-(\frac{13}{4})(x-2)^2+18$ can be used to find the height of ball after x seconds.

To find the time it will take the ball to hit the ground, we will substitute y equals 0 in our equation.

$0=-(\frac{13}{4})(x-2)^2+18$

$0-18=-(\frac{13}{4})(x-2)^2+18-18$

$0-18=-(\frac{13}{4})(x-2)^2$

$-18*(\frac{4}{13})=-(x-2)^2$

$\frac{72}{13}=(x-2)^2$

Taking square root of both sides of our equation we will get,

$\sqrt{\frac{72}{13}}=x-2$

$x-2\pm 2.35339$

$x-2=2.35339\text{ (or) } x-2=2.35339$

$x-2+2=2.35339+2\text{ (or) } x-2+2=-2.35339+2$

$x=4.35339\text{ (or) } x=-0.35339$

$x\approx 4.35\text{ (or) } x\approx -0.35$

Since time can not be negative, therefore, the ball will hit the ground approximately after 4.35 seconds.

7 0

3 years ago

U

katen-ka-za [31]

Answer:

x = 4/7

y = 60/7

Step-by-step explanation:

3x + 4y = 36

y = x + 8

Substitute the second equation into the first since it already has the y isolated for you:

3x + 4(x + 8) = 36

3x + 4x + 32 = 36

7x = 4

x = 4/7

Take the answer you got from the equation above and plug that into the second equation:

y = 4/7 + 8

y = 60/7

To check just LS/RS both equations:

3(4/7) + 4(60/7) = 36

12/7 = 240/7 = 36

252/7 = 36

36 = 36

LS = RS

60/7 = 4/7 + 8

60/7 = 60/7

LS = RS

8 0

3 years ago

Is my answer correct? Please see attachment and notify me.

statuscvo [17]

Last time I checked that was about right, but it's been a few years since then.

6 0

3 years ago

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Carlos has $50 and is saving $3 a day. Sally has $14 and is saving $5 a day. As soon as possible.

WARRIOR [948]

Answer: ...well can you be a little specific please¿

Step-by-step explanation:

6 0

3 years ago

Maria kept a log of the number of miles she jogged each time she went for a run as she trained for an upcoming marathon. She dis

CaHeK987 [17]

Answer:

Step-by-step explanation:

Let's recall that for calculating the range of a data set, we have to find out the lowest and the highest values of the data set.

As we can see in the graph below, the lowest value in the histogram is 1 and the highest is 7.99, therefore the correct answer is:

4 0

3 years ago

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