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Elza [17]
3 years ago
11

The number of bacteria (b) in a batch of refrigerated food is given by the function b(t) = 20t2 − 70t + 300, where t is the temp

erature of the food in degrees Fahrenheit. The function t(h) = 2h + 3 gives the temperature of the food h hours after it is removed from refrigeration. Which expression correctly represents the number of bacteria (b) in the food as a function of the number of hours (h) the food is unrefrigerated?
Mathematics
1 answer:
Mazyrski [523]3 years ago
4 0
b(t)=20t^2-70t+300 represent the number of bacteria in a batch of refrigerated food, and t(h) represent the temperature of the food h hours after it is removed from refrigeration. To find the number of bacteria as function of the number of hours the food is refrigerated, we are going to find the composite function (b ∘ t). To do it, we are going to evaluate our first functions b(t) at our second function t(h):
b(t)=20t^2-70t+300
t(h)=2h+3
b(2h+3)=20(2h+3)^2-70(2h+3)+300
b(2h+3)=20(4h^2+12h+9)-140h-210+300
b(2h+3)=80h^2+240h+180-140h+90
b(2h+3)=80h^2+100h+270

We can conclude that the expression that represent <span>the number of bacteria (b) in the food as a function of the number of hours (h) the food is unrefrigerated is </span>b(h)=80h^2+100h+270
You might be interested in
What is the solution set of (x-2)(x-3)=3
natali 33 [55]

Answer:

x =(5-√13)/2= 0.697

x =(5+√13)/2= 4.303

Step-by-step explanation:

Step  1  :

Equation at the end of step  1  :

 (x - 2) • (x - 3) -  3  = 0  

Step  2  :

Trying to factor by splitting the middle term

2.1     Factoring  x2-5x+3  

The first term is,  x2  its coefficient is  1 .

The middle term is,  -5x  its coefficient is  -5 .

The last term, "the constant", is  +3  

Step-1 : Multiply the coefficient of the first term by the constant   1 • 3 = 3  

Step-2 : Find two factors of  3  whose sum equals the coefficient of the middle term, which is   -5 .

     -3    +    -1    =    -4  

     -1    +    -3    =    -4  

     1    +    3    =    4  

     3    +    1    =    4  

Observation : No two such factors can be found !!

Conclusion : Trinomial can not be factored

Equation at the end of step  2  :

 x2 - 5x + 3  = 0  

Step  3  :

Parabola, Finding the Vertex :

3.1      Find the Vertex of   y = x2-5x+3

Parabolas have a highest or a lowest point called the Vertex .   Our parabola opens up and accordingly has a lowest point (AKA absolute minimum) .   We know this even before plotting  "y"  because the coefficient of the first term, 1 , is positive (greater than zero).  

Each parabola has a vertical line of symmetry that passes through its vertex. Because of this symmetry, the line of symmetry would, for example, pass through the midpoint of the two  x -intercepts (roots or solutions) of the parabola. That is, if the parabola has indeed two real solutions.  

Parabolas can model many real life situations, such as the height above ground, of an object thrown upward, after some period of time. The vertex of the parabola can provide us with information, such as the maximum height that object, thrown upwards, can reach. For this reason we want to be able to find the coordinates of the vertex.  

For any parabola,Ax2+Bx+C,the  x -coordinate of the vertex is given by  -B/(2A) . In our case the  x  coordinate is   2.5000  

Plugging into the parabola formula   2.5000  for  x  we can calculate the  y -coordinate :  

 y = 1.0 * 2.50 * 2.50 - 5.0 * 2.50 + 3.0

or   y = -3.250

Parabola, Graphing Vertex and X-Intercepts :

Root plot for :  y = x2-5x+3

Axis of Symmetry (dashed)  {x}={ 2.50}  

Vertex at  {x,y} = { 2.50,-3.25}  

x -Intercepts (Roots) :

Root 1 at  {x,y} = { 0.70, 0.00}  

Root 2 at  {x,y} = { 4.30, 0.00}  

Solve Quadratic Equation by Completing The Square

3.2     Solving   x2-5x+3 = 0 by Completing The Square .

Subtract  3  from both side of the equation :

  x2-5x = -3

Now the clever bit: Take the coefficient of  x , which is  5 , divide by two, giving  5/2 , and finally square it giving  25/4  

Add  25/4  to both sides of the equation :

 On the right hand side we have :

  -3  +  25/4    or,  (-3/1)+(25/4)  

 The common denominator of the two fractions is  4   Adding  (-12/4)+(25/4)  gives  13/4  

 So adding to both sides we finally get :

  x2-5x+(25/4) = 13/4

Adding  25/4  has completed the left hand side into a perfect square :

  x2-5x+(25/4)  =

  (x-(5/2)) • (x-(5/2))  =

 (x-(5/2))2

Things which are equal to the same thing are also equal to one another. Since

  x2-5x+(25/4) = 13/4 and

  x2-5x+(25/4) = (x-(5/2))2

then, according to the law of transitivity,

  (x-(5/2))2 = 13/4

We'll refer to this Equation as  Eq. #3.2.1  

The Square Root Principle says that When two things are equal, their square roots are equal.

Note that the square root of

  (x-(5/2))2   is

  (x-(5/2))2/2 =

 (x-(5/2))1 =

  x-(5/2)

Now, applying the Square Root Principle to  Eq. #3.2.1  we get:

  x-(5/2) = √ 13/4

Add  5/2  to both sides to obtain:

  x = 5/2 + √ 13/4

Since a square root has two values, one positive and the other negative

  x2 - 5x + 3 = 0

  has two solutions:

 x = 5/2 + √ 13/4

  or

 x = 5/2 - √ 13/4

Note that  √ 13/4 can be written as

 √ 13  / √ 4   which is √ 13  / 2

Solve Quadratic Equation using the Quadratic Formula

3.3     Solving    x2-5x+3 = 0 by the Quadratic Formula .

According to the Quadratic Formula,  x  , the solution for   Ax2+Bx+C  = 0  , where  A, B  and  C  are numbers, often called coefficients, is given by :

                                     

           - B  ±  √ B2-4AC

 x =   ————————

                     2A

 In our case,  A   =     1

                     B   =    -5

                     C   =   3

Accordingly,  B2  -  4AC   =

                    25 - 12 =

                    13

Applying the quadratic formula :

              5 ± √ 13

  x  =    —————

                   2

 √ 13   , rounded to 4 decimal digits, is   3.6056

So now we are looking at:

          x  =  ( 5 ±  3.606 ) / 2

Two real solutions:

x =(5+√13)/2= 4.303

or:

x =(5-√13)/2= 0.697

4 0
3 years ago
Read 2 more answers
Pls help I will mark brainlyesd
aev [14]
First, we have to solve for x by isolating it on one side.
6x + 10 = -8
(Subtract 10 from both sides)
6x = -18
(Divide both sides by 6)
x = -3

On option C, x is on -3, so that would be the correct answer
7 0
2 years ago
A garden has a length of 20 ft. It has a width of 12 ft. What is the area of the garden ?
Crazy boy [7]

Answer:

The answer for your problem is 240

Step-by-step explanation:

A=wl=12·20=240

for this problem all you had to do was multiply

12*20 to get your answer

6 0
3 years ago
Anyone can help asap?
Varvara68 [4.7K]

Company A: 120 + 0.50x

Company B: 60 + 0.60x

Company A = Company B (solve for x)

(Here, x = miles)


120 + 0.50x = 60 + 0.60x

120 - 60 = 0.60x - 0.50x

60 = 0.10x

600 = x

7 0
3 years ago
5P
BigorU [14]
Yup here you go it’s uhmmmm idk anymore heheh
6 0
2 years ago
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