What's the answer ????????

Find the quadratic function that fits the following data. which one function fits.

Oksana_A [137]

Answer:

C

Step-by-step explanation:

The general rule for the quadratic function is

$y=ax^2+bx+c$

Use the data from the table:

$y(50)=130\Rightarrow 130=a\cdot 50^2+b\cdot 50+c\\ \\y(70)=130\Rightarrow 130=a\cdot 70^2+b\cdot 70+c\\ \\y(90)=200\Rightarrow 200=a\cdot 90^2+b\cdot 90+c$

We get the system of three equations:

$\left\{\begin{array}{l}2500a+50b+c=130\\ \\4900a+70b+c=130\\ \\8100a+90b+c=200\end{array}\right.$

Subtract these equations:

$\left\{\begin{array}{l}4900a+70b+c-2500a-50b-c=130-130\\ \\8100a+90b+c-2500a-50b-c=200-130\end{array}\right.\Rightarrow \left\{\begin{array}{l}2400a+20b=0\\ \\5600a+40b=70\end{array}\right.$

From the first equation

$b=-120a$

Substitute it into the second equation:

$5600a+40\cdot (-120a)=70\Rightarrow 800a=70,\\ \\ a=\dfrac{7}{80},\\ \\ b=-120\cdot \dfrac{7}{80}=-\dfrac{21}{2}=-10.5$

So,

$2500\cdot \dfrac{7}{80}+50\cdot (-10.5)+c=130\Rightarrow 218.75-525+c=130\\ \\c=130-218.75+525=436.25$

The quadratic function is

$y=\dfrac{7}{80}x^2-10.5x+436.25\\ \\y=0.0875x^2-10.5x+436.25$

4 0

3 years ago

The length of a rectangular garden ABCD is 9 feet more than its width. It is surrounded by a brick walkway 4 feet wide as shown

Anna71 [15]

Answer:

16.5 ft by 25.5 ft

Step-by-step explanation:

Let w represent the width of the garden in feet. Then w+9 is the garden's length, and w(w+9) represents its area.

The surrounding walkway adds 8 feet to each dimension, so the total area of the garden with the walkway is ...

(w+8)(w+9+8) = w^2 +25w +136

If we subtract the area of the garden itself, then the remaining area is that of the walkway:

(w^2 +25w +136) - (w(w+9)) = 400

16w + 136 = 400 . . .simplify

16w = 264 . . . . . . . . subtract 136

264/16 = w = 16.5 . . . . . width of the garden in feet

w+9 = 25.5 . . . . . . . . . . .length of the garden in feet

5 0

3 years ago

A store is having a sale on jelly beans and trail mix. For 6 pounds of jelly beans and 2 pounds of trail mix, the total cost is

Aneli [31]

Answer:

Jelly Bean price per pound = $3.25, Trail Mix price per pound = $1.25

Step-by-step explanation:

Let jb = price per pound of jelly beans

Let tm = price per pound of trail mix

equation 1 -> 6*jb + 2*tm = 22

equation 2 -> 3*jb + 5*tm = 16

simplify equation 1

6*jb + 2tm = 22

2*tm = 22 - 6*jb

divide by 2

tm = 11 - 3*jb

plug this into equation 2

3*jb + 5*tm = 16

3*jb + 5*(11-3*jb) = 16

3*jb + 55 - 15*jb = 16

-12*jb + 55 = 16

-12*jb = 16 - 55

-12*jb = -39

jb = -39/-12

jb = 3.25

then, plug the cost per pound of jelly beans back into the simplified equation 1

tm = 11 - 3*jb

tm = 11 - 3*3.25

tm = 1.25

3 0

2 years ago

Try to estimate the probability you'd turn on the radio and hear a song you were thinking about. In other words, estimate the pr

Black_prince [1.1K]

Probabilities are used to determine the likelihood of events

The value of the probability P(thinking of a song)P(turn on the radio and hear the song) is 0.056

<h3>How to estimate the probability</h3>

To calculate the probability, we make use of the following representations:

Event A represents the likelihood of thinking of a song
Event B represents the likelihood of turning on the radio and hearing the song

So, we have:

P(thinking of a song)P(turn on the radio and hear the song) = P(A) * P(B)

Assume that:

P(A) = 0.12 and P(B) = 0.47

So, we have:

P(thinking of a song)P(turn on the radio and hear the song) = 0.12* 0.47

Evaluate the product

P(thinking of a song)P(turn on the radio and hear the song) = 0.0564

Approximate

P(thinking of a song)P(turn on the radio and hear the song) = 0.056

Hence, the value of the probability P(thinking of a song)P(turn on the radio and hear the song) is 0.056