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allsm [11]
3 years ago
14

Solve the system of equations using the elimination method 2x + 9y = -40

Mathematics
1 answer:
Ber [7]3 years ago
7 0
Wait like find the variables number ?
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Shelley designed the patio below, in which one side of the patio is a wall of the house. The length of each side of a square on
Nana76 [90]
$120 because the fencing of the patio would use up eight squares and each square in the picture is 3 meters so we would need 24 meters of fencing to cover up the entire patio. Since it cost $5 for one meter, 5*24 is $120.
3 0
3 years ago
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Using a savings amount of $450, assume you deposited the total amount
ankoles [38]

Answer:

<h2> 7.3%</h2>

Step-by-step explanation:

Using the formula for calculating the simple interest to get the rate of return;

Simple Interest = Principal * Rate * Time/100

Given Principal = $450,

Time (in years) = 1 year

Simple interest = $32.75

Rate (in %) =?

Substituting the given values in the given formula to get the rate;

32.75 = 450*1*R/100

450R = 3275

R = 3,275/450

R = 7.3%

The rate of return is  7.3%

4 0
3 years ago
What are the solutions of 4(x+6)^2=52
zysi [14]

ANSWER: 1.211 or 13.211

Step-by-step explanation:

STEP

1

:

1.1     Evaluate :  (x-6)2   =    x2-12x+36  

Trying to factor by splitting the middle term

1.2     Factoring  x2-12x-16  

The first term is,  x2  its coefficient is  1 .

The middle term is,  -12x  its coefficient is  -12 .

The last term, "the constant", is  -16  

Step-1 : Multiply the coefficient of the first term by the constant   1 • -16 = -16  

Step-2 : Find two factors of  -16  whose sum equals the coefficient of the middle term, which is   -12 .

     -16    +    1    =    -15  

     -8    +    2    =    -6  

     -4    +    4    =    0  

     -2    +    8    =    6  

     -1    +    16    =    15  

Observation : No two such factors can be found !!

Conclusion : Trinomial can not be factored

Equation at the end of step

1

:

 x2 - 12x - 16  = 0  

STEP

2

:

Parabola, Finding the Vertex

2.1      Find the Vertex of   y = x2-12x-16

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   6.0000  

Plugging into the parabola formula   6.0000  for  x  we can calculate the  y -coordinate :  

 y = 1.0 * 6.00 * 6.00 - 12.0 * 6.00 - 16.0

or   y = -52.000

Parabola, Graphing Vertex and X-Intercepts :

Root plot for :  y = x2-12x-16

Axis of Symmetry (dashed)  {x}={ 6.00}  

Vertex at  {x,y} = { 6.00,-52.00}  

x -Intercepts (Roots) :

Root 1 at  {x,y} = {-1.21, 0.00}  

Root 2 at  {x,y} = {13.21, 0.00}  

Solve Quadratic Equation by Completing The Square

2.2     Solving   x2-12x-16 = 0 by Completing The Square .

Add  16  to both side of the equation :

  x2-12x = 16

Now the clever bit: Take the coefficient of  x , which is  12 , divide by two, giving  6 , and finally square it giving  36  

Add  36  to both sides of the equation :

 On the right hand side we have :

  16  +  36    or,  (16/1)+(36/1)  

 The common denominator of the two fractions is  1   Adding  (16/1)+(36/1)  gives  52/1  

 So adding to both sides we finally get :

  x2-12x+36 = 52

Adding  36  has completed the left hand side into a perfect square :

  x2-12x+36  =

  (x-6) • (x-6)  =

 (x-6)2

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

  x2-12x+36 = 52 and

  x2-12x+36 = (x-6)2

then, according to the law of transitivity,

  (x-6)2 = 52

We'll refer to this Equation as  Eq. #2.2.1  

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

Note that the square root of

  (x-6)2   is

  (x-6)2/2 =

 (x-6)1 =

  x-6

Now, applying the Square Root Principle to  Eq. #2.2.1  we get:

  x-6 = √ 52

Add  6  to both sides to obtain:

  x = 6 + √ 52

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

  x2 - 12x - 16 = 0

  has two solutions:

 x = 6 + √ 52

  or

 x = 6 - √ 52

Solve Quadratic Equation using the Quadratic Formula

2.3     Solving    x2-12x-16 = 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   =   -12

                     C   =  -16

Accordingly,  B2  -  4AC   =

                    144 - (-64) =

                    208

Applying the quadratic formula :

              12 ± √ 208

  x  =    ——————

                     2

Can  √ 208 be simplified ?

Yes!   The prime factorization of  208   is

  2•2•2•2•13  

To be able to remove something from under the radical, there have to be  2  instances of it (because we are taking a square i.e. second root).

√ 208   =  √ 2•2•2•2•13   =2•2•√ 13   =

               ±  4 • √ 13

 √ 13   , rounded to 4 decimal digits, is   3.6056

So now we are looking at:

          x  =  ( 12 ± 4 •  3.606 ) / 2

Two real solutions:

x =(12+√208)/2=6+2√ 13 = 13.211

or:

x =(12-√208)/2=6-2√ 13 = -1.211

6 0
3 years ago
Read 2 more answers
If Gabe's Soccer Ball Company is able, due to competitive pressure, to charge $60 for a new soccer ball, while one soccer ball c
Brums [2.3K]

Answer:

Results are below.

Step-by-step explanation:

Giving the following information:

Selling price= $60

Unitary variable cost= $28

Fixed costs= $15,000

<u>First, we need to calculate the average total cost:</u>

Average cost= total cost / number of units

For example, for 1 unit and 10,000 units:

1 unit:

Average cost= 15,028/1 = 15,028

10,000 units:

Average cost= (15,000 + 28*10,000) / 10,000

Average cost= $29.5

<u>Now, we can calculate the break-even point in units:</u>

<u></u>

0= (60*x) - (28*x) - 15,000

x= number of units to break-even

0= 32x - 15,000

15,000/32= x

468.75=x

break-even point in units= 469

<u>For the desired profit of $10,000:</u>

10,000 = (60*x) - (28*x) - 15,000

25,000= 32x

781.25= x

Break-even point= 782 units

<u>Finally, fixed costs dropped by $8,000:</u>

0= 32x - 7,000

x= 7,000/32

x= 218.75

Break-even point= 219

Difference= 250 units

5 0
3 years ago
A function has y-intercept of -2 and a slope of -1. which equation below describes the function?
ozzi
The correct equation should look something like this:
y= -1x - 2

Consider the equation for a line:
y = mx + b,
Where ‘m’ is the slope
Where ‘b’ is the y-intercept.

From there you can plug in your known values for ‘m’ and ‘b’, and get the equation above. If you are still not convinced, I suggest you graph the function and observe its slope and y-intercept.

Hope this helps!
8 0
3 years ago
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