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Use Lagrange multipliers to find the volume of the largest rectangular box in the first octant with three faces in the coordinat

tensa zangetsu [6.8K]

Answer:

The volume of the largest rectangular box (V) = 81/4

Step-by-step explanation:

Step 1:-

Given volume of the largest rectangular box in the first octant

V = l b h

let (x ,y, z) be the one vertex in the given plane

V = f(x, y, z) = x y z

given plane. Ф (x, y, z) = x + 9y + 4z = 27 ........(1)

Step( ii):

By using Lagrange multipliers

Suppose it is required to find the extreme for the function f(x, y, z) subject to the condition Ф (x, y, z) =0

Form Lagrange function F(x, y, z) = f(x, y, z) + λ Ф (x, y, z) where λ is called the Lagrange multipliers

F(x, y, z) = x y z+ λ ( x + 9y + 4z - 27) ......(2)

Obtain the equations are δ F / δ x = 0

δ f / δ x +λ δ Ф / δ x =0

⇒ y z + λ ( 1) = 0

⇒ y z = - λ ......(a)

Obtain the equations are δ F / δ y = 0

δ f / δ x +λ δ Ф / δ x =0

⇒ x z + λ ( 9) = 0

⇒ $\frac{xz}{9}$ = - λ .......(b)

Obtain the equations are δ F / δ z = 0

δ f / δ x +λ δ Ф / δ z =0

x y + λ ( 4) = 0

⇒ $\frac{xy}{4}$ = - λ .......(c)

Step (iii):-

Equating (a) and (b) equations

we get $y z = \frac{xz}{9}$

cancel 'z' value we get x = 9y .......(d)

Equating (b) and (c) equations

we get $\frac{xy}{4} = \frac{xz}{9}$

cancel 'x' value on both sides , we get

4z =9y ......(e)

substitute (d) (e) values in equation (1) we get

x + 9y + 4z -27 = 0

9y + 9y + 9y -27 =0

27y -27 =0

y = 1

substitute y =1 in x = 9y

x = 9

substitute y =1 in 4z =9y

z = 9 /4

therefore the dimensions are x =9 , y=1 and z = 9 /4

Conclusion:-

The largest volume of the rectangular box V = x y z

substitute x =9 , y=1 and z = 9 /4

V = 9(1)(9/4) =81/4

The largest volume of the rectangular box (V) = 81/4

Verification :-

Given plane x + 9y + 4z = 27

substitute x =9 , y=1 and z = 9 /4

9 + 9 + 4(9/4) = 27

27 =27

so satisfied equation

3 0

4 years ago

2) WILL MARK BRAINLIEST + 10 POINTS! :) HAPPY NEW YEAR!~!!!!!!!!!!!

Annette [7]

We can write the sequence out more fully, as we can see each time it is divided by 6.
60, 60/6, 60/6^2, 60/6^3, and so on.
Therefore we know the sequence can be written as $u_n= \frac{60}{6^{n-1}}$
You can think of this as a graph, i.e. y=60/6^(x-1)
As a result, as x tends to infinity, y tends to 0 (since it effectively becomes 60/infinity). Therefore the sequence converges toward zero.

5 0

3 years ago

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What's -54 divided by 104 ?

tatuchka [14]

Your answer is -0.51923077

6 0

3 years ago

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Given: NQ is an altitude of △MNP

Virty [35]

Answer:

Statement: Reason:

ΔNQM and ΔNQP are right triangle Definition of a right triangle

SinM = h/p and SinP = h/m Definition of sine ratio

p sin M = m sin P Substitution property of equality

p sin M / pm = msinP / pm Division property of equality.

8 0

4 years ago

Show in fact that 1=9m + 20n for some integers m and n

marta [7]

Answer:

$1=9\cdot 9+20\cdpt (-4)=81-80$

Step-by-step explanation:

The greatest common divisor between 9 and 20 is 1, so we know the equation $1=9m+20n$ has a solution. A solution can be found either by inspection, or by applying Euclidean algorithm.

By inspection we just list some multiples of 9:

9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99

and also list some mutiples of 20:

20, 40, 60, 80, 100, 120

And so we see that we can find a multiple of 9 (81) which is 1 away from a multiple of 20 (80). Which is the solution given at the start.

For the Euclidean algorithm, we should divide the greatest of the two numbers, by the smallest one, and keep track of the remainder:

20 = 9 * 2 + 2

Then we divide 9 by the remainder we got, which is 2:

9 = 2 * 4 + 1

we would continue doing this until getting a remainder of 1 (which we just did). Finally we "solve" for 1, from the last equation:

9 - 2*4 = 1

And then we solve for 2 from the first equation, and plug that in into the previous equation:

20 - 9*2 =2

9 - ( 20 - 9*2)*4 = 1

which does give us the same solution: $9\cdot 9 +20\cdot (-4)=1$

5 0

4 years ago