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laila [671]
3 years ago
13

Ef is the median of trapezoid abcd (please explain the answer im so confused lol)

Mathematics
1 answer:
Art [367]3 years ago
4 0

Step-by-step explanation:

Okay, so...

The Median of a trapezoid is directly in the middle. For some weird mathimatical reason you won't ever need to know unless it's on an exam or you become a math major, its midsegment is the average of the top length and the bottom length.

In other words,

EF = ( BC + AD ) / 2

So for part 1, we can use that equation to find x.

EF = ( BC + AD ) / 2

  • Insert known equations.

4x-18=[(x+12)+(3x-4)]/2

  • Simplify within parentheses.

4x-18=[x+12+3x-4]/2

4x-18=[x+3x+12-4]/2

  • Add.

4x-18=[4x+8]/2

  • Divide.

4x-18=2x+4

  • Simplify.

(4x-2x) +(-18+18)=(2x-2x)+(4+18)

2x=22

  • Divide both sides by 2.

x=11

Part 2 is a lot easier now. All we have to do is plug in 11 for x.

BC =x+12

BC = 11+12

BC = 23

-

AD = 4x-18

AD = 4(11)-18

AD = 44-18

AD = 26

-

EF = 3x-4

EF = 3(11)-4

EF = 33-4

EF = 29

Answer:

Part I: x = 11

Part II:

  • BC = 23
  • AD = 26
  • EF = 29
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Naomi pays $1.50 each time she rides the city bus. She has already ridden the bus 18 times so far this year. The expression repr
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3 years ago
Solve the system of equations.
Ksenya-84 [330]

Answer:

1) {y,x}={-3,-23}

2) {x,y}={7,-9/2}

Step-by-step explanation:

Required:

  • Solve systems of equations

1) y - x = 20, 2x - 15y = -1

Equations Simplified or Rearranged :

[1]    y - x = 20

  [2]    -15y + 2x = -1

Graphic Representation of the Equations :

x + y = 20        2x - 15y = -1  

Solve by Substitution :

// Solve equation [1] for the variable  y

 [1]    y = x + 20

// Plug this in for variable  y  in equation [2]

  [2]    -15•(x +20) + 2x = -1

  [2]     - 13x = 299

// Solve equation [2] for the variable  x

[2]    13x = - 299

  [2]    x = - 23

// By now we know this much :

  y = x+20

   x = -23

// Use the  x  value to solve for  y

   y = (-23)+20 = -3

Solution :

{y,x} = {-3,-23}

2) 25-x=-4y,3x-2y=30

Equations Simplified or Rearranged :

  [1]    -x + 4y = -25

  [2]    3x - 2y = 30

Graphic Representation of the Equations :

   4y - x = -25        -2y + 3x = 30  

Solve by Substitution :

// Solve equation [1] for the variable  x

  [1]    x = 4y + 25

// Plug this in for variable  x  in equation [2]

 [2]    3•(4y+25) - 2y = 30

  [2]    10y = -45

// Solve equation [2] for the variable  y

  [2]    10y = - 45

  [2]    y = - 9/2

// By now we know this much :

  x = 4y+25

   y = -9/2

// Use the  y  value to solve for  x

  x = 4(-9/2)+25 = 7

Solution :

{x,y} = {7,-9/2}

3 0
2 years ago
Paul is saving for a down payment to buy a house. The account earns 13% interest compound quarterly, and he wants to have $15,00
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Answer:

The principal must be = $8991.88

Step-by-step explanation:

Formula for compound interest is:

A = P(1 + \frac{r}{n})^{nt}

Where A is the amount after 't' years.

P is the principal amount

n is the number of times interest is compounded each year.

r is the rate of interest.

Here, we are given that:

Amount, A = $15000

Rate of interest = 13 % compounded quarterly i.e. 4 times every year

Number of times, interest is compounded each year, n = 4

Time, t = 4 years.

To find, Principal P = ?

Putting all the given values in the formula to find P.

15000 = P(1 + \frac{13}{400})^{4\times 4}\\\Rightarrow 15000 = P(1 + 0.0325)^{16}\\\Rightarrow 15000 = P(1.0325)^{16} \\\Rightarrow 15000 = P \times 1.66817253\\\Rightarrow P = \dfrac{15000}{1.66817253}\\\Rightarrow P \approx \$8991.88

So, <em>the principal must be = $8991.88</em>

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Please help. Only if you know it.
andrew11 [14]

Answer:

C (Lake Depth Answer)

Step-by-step explanation:

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This leaves us back where we started, with 0.

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This leaves us with $5, not 0.

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