AAAAAAAAAAAAAAAAAA Help please ;-;

a cook needs 12 pounds of flour he wants to spend the least amount of money if a 2 pound bag costs $1.59 and a 5 pound bag costs

Virty [35]

He should buy two 5 pound bags and one 2 pound bag.

4 0

3 years ago

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The plane x + y + z = 12 intersects paraboloid z = x^2 + y^2 in an ellipse.(a) Find the highest and the lowest points on the ell

emmasim [6.3K]

Answer:

a)

Highest (-3,-3)

Lowest (2,2)

b)

Farthest (-3,-3)

Closest (2,2)

Step-by-step explanation:

To solve this problem we will be using Lagrange multipliers.

a)

Let us find out first the restriction, which is the projection of the intersection on the XY-plane.

From x+y+z=12 we get z=12-x-y and replace this in the equation of the paraboloid:

$\bf 12-x-y=x^2+y^2\Rightarrow x^2+y^2+x+y=12$

completing the squares:

$\bf x^2+y^2+x+y=12\Rightarrow (x+1/2)^2-1/4+(y+1/2)^2-1/4=12\Rightarrow\\\\\Rightarrow (x+1/2)^2+(y+1/2)^2=12+1/2\Rightarrow (x+1/2)^2+(y+1/2)^2=25/2$

and we want the maximum and minimum of the paraboloid when (x,y) varies on the circumference we just found. That is, we want the maximum and minimum of

$\bf f(x,y)=x^2+y^2$

subject to the constraint

$\bf g(x,y)=(x+1/2)^2+(y+1/2)^2-25/2=0$

Now we have

$\bf \nabla f=(\displaystyle\frac{\partial f}{\partial x},\displaystyle\frac{\partial f}{\partial y})=(2x,2y)\\\\\nabla g=(\displaystyle\frac{\partial g}{\partial x},\displaystyle\frac{\partial g}{\partial y})=(2x+1,2y+1)$

Let $\bf \lambda$ be the Lagrange multiplier.

The maximum and minimum must occur at points where

$\bf \nabla f=\lambda\nabla g$

that is,

$\bf (2x,2y)=\lambda(2x+1,2y+1)\Rightarrow 2x=\lambda (2x+1)\;,2y=\lambda (2y+1)$

we can assume (x,y)≠ (-1/2, -1/2) since that point is not in the restriction, so

$\bf \lambda=\displaystyle\frac{2x}{(2x+1)} \;,\lambda=\displaystyle\frac{2y}{(2y+1)}\Rightarrow \displaystyle\frac{2x}{(2x+1)}=\displaystyle\frac{2y}{(2y+1)}\Rightarrow\\\\\Rightarrow 2x(2y+1)=2y(2x+1)\Rightarrow 4xy+2x=4xy+2y\Rightarrow\\\\\Rightarrow x=y$

Replacing in the constraint

$\bf (x+1/2)^2+(x+1/2)^2-25/2=0\Rightarrow (x+1/2)^2=25/4\Rightarrow\\\\\Rightarrow |x+1/2|=5/2$

from this we get

and the candidates for maximum and minimum are (2,2) and (-3,-3).

Replacing these values in f, we see that

f(-3,-3) = 9+9 = 18 is the maximum and

f(2,2) = 4+4 = 8 is the minimum

b)

Since the square of the distance from any given point (x,y) on the paraboloid to (0,0) is f(x,y) itself, the maximum and minimum of the distance are reached at the points we just found.

We have then,

(-3,-3) is the farthest from the origin

(2,2) is the closest to the origin.

3 0

3 years ago

Please help, having a hard time

rosijanka [135]

Answer:

The balcony seat costs $9, the orchestra seat costs $9 + $6 = $15.

Step-by-step explanation:

Let x is the cost/price of one balcony seat, in dollars.

Then the cost of one orchestra seat is (x+6) dollars, according to the condtion.

The total cost of tickets is

250x + 400*(x+6) = 8250.

Simplify it step by step.

250x + 400x + 2400 = 8250,

650x = 8250 - 2400 = 5850 ====> x = 5850/650 = 9.

Answer. The balcony seat costs $9, the orchestra seat costs $9 + $6 = $15.

Check. 9*250 + 15*400 = 8250. Correct.

3 0

3 years ago

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Need this quickly!! im not good in math so .

oksano4ka [1.4K]

In algebra, symbols are used to represent numbers. Example: 5x=20 or 4x=24

5 0

3 years ago

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i’m having some trouble with these three questions it would be a big help if someone could help me out :)

algol [13]

I’m not sure if I’m right but I think u have to add the 3 largest numbers in the population section and then add the other 3 least numbers in the same section and then u have to subtract those 2 answers.

I’m really bad at explaining but I hope u get it

6 0

3 years ago

AAAAAAAAAAAAAAAAAA Help please ;-;​

AAAAAAAAAAAAAAAAAA Help please ;-;