Answer:
The answer is below
Step-by-step explanation:
A circle is the locus of a points such that its distance from a fixed point is always constant.
Since the drone moves in a circular path, therefore the path of the drone forms a circle. The equation of a circle is given by:
(x - h)² + (y - k)² = r²; where (h, k) is the center of the circle and r is the radius of the circle.
Danny is located at the origin. Since the drone flies in a circular path around an object that is 210 feet west and 220 feet south of his position. Hence the center of the circular path is (-210, -220).
Also, the drone's path takes it over a point that is 160 feet east and 160 feet south of him i.e. (160, -160). Therefore the radius of the circle is the distance between point (-210, -220) and point (160, -160)
Using (x - h)² + (y - k)² = r²:
[x - (-210)]² + [y - (-220)]² = (√140500)²
(x + 210)² + (y + 220)² = 140500
x² + 420x + 44100 + y² + 440y + 48400 = 140500
x² + y² + 420x + 440y - 48000 = 0
Answer :
Given expression is
To make perfect square trinominal we use completing the square method
In completing the square method we add and subtract the half of square of coefficient of middle term
Here coefficient of middle term is -7
Half of -7 is
Square of is
=
So the expression becomes that gives perfect square trinomial
Hence , the value of 'c' is
Answer:
Amanda buy first kind of pen = 3
Amanda buy second kind of pen = 2
Amanda buy third kind of pen = 15
Step-by-step explanation:
Given - Amanda went to the store to purchase ink pens. She found three
kinds of pens. The first cost $4 each; the price of the second kind
was 4 for $1; and the cost for the third kind was 2 for $1. She bought
20 pens and she bought at least one of each kind. (It is possible to
buy only 1 of the pens that are "4 for $1" or "2 for $1".) The cost was
$20.
To find - When she got back to her office, Amanda decided to turn this into
a math problem for me. She asked: how many of each kind did I
buy?
Proof -
Let Amanda buy first kind of pen = x
second kind of pen = y
third kind of pen = z
As given,
She bought total pen = 20
⇒x + y + z = 20 ...............(1)
Now,
As given,
cost for first kind pen = $4 for 1 pen
As she bought x pens of first kind , so
Cost of x pens of first kind = $4x
Now,
The price of the second kind was 4 for $1
⇒Cost of second kind = $ for 1 pen
As she bought y pens of send kind , so
Cost of y pens of second kind = $
Now,
The price of the third kind was 2 for $1
⇒Cost of third kind = $ for 1 pen
As she bought z pens of send kind , so
Cost of z pens of third kind = $
Now,
As given, The cost was $20
⇒4x + +
= 20
⇒16x + y + 2z = 80 .....................(2)
∴ we get 2 equations
x + y + z = 20 .....................(1)
16x + y + 2z = 80 .....................(2)
Now,
Subtract equation (1) from equation (2) , we get
16x + y + 2z - ( x+ y + z )= 80 - 20
⇒16x + y + 2z - x - y - z = 60
⇒15x + z = 60
⇒z = 60 - 15x
Now,
Put the value of z in equation (1) , we get
x + y + 60 - 15 x = 20
⇒ y - 14x = 20 - 60
⇒y - 14x = -40
⇒14x - y = 40
⇒y = 14x - 40
Now,
we get
z = 60 - 15x
y = 14x - 40
As given
she bought at least one of each kind
it means x > 1, y > 1, z > 1
Now,
If x = 1, then y = 14 - 40 = -26
Not possible
If x = 2 , then y = 14(2) - 40 = -12
Not possible
If x = 3, then y = 14(3) - 40 = 2 and z = 60 - 15(3) = 15
Possible.
If x = 4, then y = 14(4) - 40 = 16 and z = 60 - 15(4) = 0
Not Possible.
If x = 5, then y = 14(5) - 40 = 30 and z = 60 - 15(5) = -15
Not Possible.
∴ we get
x = 3, y = 2, z = 15
Amanda buy first kind of pen = x = 3
Amanda buy second kind of pen = y = 2
Amanda buy third kind of pen = z = 15