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Illusion [34]
3 years ago
14

Mary and roberto bought identical backpacks at different stores. marys backpacks originally cost $65 and was discounted 25%. rob

ertos backpack orignally cost $75 and was on sale for 30% off the original price.which backpack was a better buy?
Mathematics
1 answer:
garri49 [273]3 years ago
6 0
Mary's backpack: 25% of 65 = 0.25 * 65 = 16.25; 65 - 16.25 = $48.75
Roberto's backpack: 30% of 75 = 0.3 * 75 = 22.5; 75 - 22.5 = $52.5

Mary's backpack was a better buy because it was cheaper. 
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What are the coordinates of the foci of the conic section shown below?
Naddik [55]

Answer:

((y + 2) ^ 2)/25 - ((x - 3) ^ 2)/4 = 1 O A. ( (3, - 2 plus/minus sqrt(21)) B. (3, - 2 plus/minus sqrt(29)) O B. O c. D . (3 plus/minus sqrt(21), - 2); (3 plus/minus sqrt(29), - 2)

6 0
3 years ago
PLEASE HELP GUYS i am struggling so much, two questions
ankoles [38]

Answer: the equation of the standard parabola

1) (y-6)^2 = 4 (x-1)

The equation of the standard parabola

2) (x+5)^2 = 16(y-2)

Step-by-step explanation:

<u>Explanation </u>

<u>Parabola:-</u>

The set of points in a plane whose distance from a fixed point and a constant ratio to their corresponding perpendicular distance from a fixed straight line is a conic.

Let S be a fixed point and l be a fixed straight line from any point P,the perpendicular PM is drawn to the line 'l'

  • The locus of P such that \frac{SP}{PM} = constant
  • The fixed point  'S' is called the Focus.
  • The fixed line'l 'is called the directrix of the conic
  • The constant ratio is known as the eccentricity, denoted by 'e'
  • If e=1 , the conic is called a parabola

1) <u> Step 1</u> :-

Given the focus   S = (2,6) and directrix is x=0

we know that \frac{SP}{PM}=1

now cross multiplication , we get

SP = PM

squaring on both sides,we get

SP^{2} = PM^2

step 2:-

now using distance formula is

  • \sqrt(((x_{2}-x_{1})^2+(y_{2} -y_{1} )^2)

Given S =(2,6) and P(x,y) be any point on parabola

SP^2 = (x-2)^2+(y-6)^2........(1)

Now using perpendicular distance formula

let P(x , y ) be any point on the parabola

  • \frac{ax_{1}+by_{1}+c   }{\sqrt{a^2+b^2} }

Given the directrix is x =0 and P(x,y) be any point on parabola

PM^2 = \frac{x^2}{\sqrt{1}^2 }......(2)

equating equation(1) and equation (2), on simplification

we get (x-2)^2+(y-6)^2 = x^2.....(3)

  • apply (a-b)^2 = a^2+  b^2+2 ab

now the equation (3) is

(y-6)^2 = 4 x-4

now the standard form of parabola is

(y-k)^2 = 4 a(x-h)

<u>Final answer</u>:-

(y-6)^2 = 4 (x-1)

2) <u> Explanation:-</u>

<u>step 1:</u>

Given vertex of a parabola is A(-5,2) and its focus is S(-5,6)

here the given points of 'x'co- ordinates are equal

  • Therefore the axis AS is parallel to y- axis

now the standard equation of parabola

(x-h)^2 = 4 a (y-k)

now you have to find' a' value

Given vertex of a parabola is A(-5,2) and its focus is S(-5,6)

The distance of AS = \sqrt{(-5-(-5)^2+(2-6)^2}

 on simplification we get a =4

<u>Final answe</u>r :-

the vertex (h,k) = (-5,2) and a=4

(x-h)^2 = 4 a (y-k)

The standard parabola is (x+5)^2 = 16 (y-2)

5 0
3 years ago
Sally was getting ready to go on a hiking trip with friends across part of the Appalachian Trail. They were trying to determine
dem82 [27]

Answer:

They'll walk 140.28 miles in 42 hours at that pace.

Step-by-step explanation:

In order to find the distance they can travel at a steady pace, we need to take the pace in wich they intend to travel and multiply it by the time that they intend to travel. In this case their pace is 5 miles every 1.5 hours it means that their pace is 5/1.5 = 3.34 m/h, if they travel for 42 hours they'll travel a distance of:

distance = 3.34*42 = 140.28 miles

5 0
3 years ago
2x+y=3, 5x-2y=12 how to solve this
Leviafan [203]
Start by getting one of the equations in terms of one variable, in this case lets put the first equation in terms of y

2x+y=3 ---> y=3-2x

now we plug that into the second equation

5x-2y=12 ---> 5x-2(3-2x)=12

we can then multiply and simplify

5x-2(3-2x)=12 ---> 5x-6+4x=12 ---> 9x-6=12 ---> 9x=18 ---> x=2

we can now plug x=2 into an equation to solve for y

2(2)+y=3 ---> 4+y=3 ---> y=-1
7 0
3 years ago
Read 2 more answers
The rabbit population in Jefferson County, which is currently at 8,400 rabbits, is increasing by 5% each year. How many rabbits
drek231 [11]

Answer:

11,340

Step-by-step explanation:

5% = 420 420 x 7 = 2940

2940 + 8400 = 11,340

4 0
3 years ago
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