A person has utility function u(x, y) = 100xy + x + 2y. Suppose that the price per unit of x is $2, and that the price per unit of y is $4. The person receives $1 000 that all has to be spent on the two commodities x and y. Solve the utility maximization problem

Respuesta :

Answer:

x = 250

y = 125

u(x,y) = 3125500

Step-by-step explanation:

As given,

The utility function u(x, y) = 100xy + x + 2y

[tex]P_{x}[/tex] = 2 , [tex]P_{y}[/tex] = 4

Now,

Budget constraint -

[tex]P_{x}[/tex] x + [tex]P_{y}[/tex] y = 1000

⇒2x + 4y = 1000

So,

Let v(x, y) = 2x + 4y - 1000

Now,

By Lagrange Multiplier

Δu = Δv

⇒< 100y + 1, 100x + 2 > = < 2, 4 >

By comparing, e get

100y + 1 = 2         ........(1)

100x + 2 = 4        .........(2)

Divide equation (2) to equation (1) , we get

[tex]\frac{100y + 1}{100x + 2} = \frac{1}{2}[/tex]

⇒2(100y+1) = 1(100x+2)

⇒200y + 2 = 100x + 2

⇒200y = 100x

⇒2y = x

Now,

As 2x + 4y = 1000

⇒2x + 2(2y) = 1000

⇒2x + 2x = 1000

⇒4x = 1000

⇒x = 250

Now,

As 2y = x

⇒2y = 250

⇒y = [tex]\frac{250}{2}[/tex] = 125

∴ we get

x = 250

y = 125

Now,

u(250, 125) = 100(250)(125) + 250 + 2(125)

                   = 3125000 + 250 + 250

                  = 3125000 + 500

                 = 3125500

⇒u(250, 125) = 3125500

The maximized value of the utility function is $3125500

The utility function is given as:

[tex]U(x,y) = 100xy + x + 2y[/tex]

The prices per unit are also given as:

[tex]P_x = 2[/tex]

[tex]P_y = 4[/tex]

When a person receives $1000, then the budget function is:

[tex]2x + 4y = 1000[/tex]

Divide through by 2

[tex]x + 2y = 500[/tex]

Differentiate the utility function with respect to x and y

[tex]U'(x) = 100y + 1[/tex]

[tex]U'(y) = 100x + 2[/tex]

So, we have:

[tex]U'(x) = P_x[/tex] and [tex]U'(y) = P_y[/tex]

The above equations become

[tex]100y + 1 = 2[/tex] and [tex]100x + 2 = 4[/tex]

Divide both equations

[tex]\frac{100y + 1}{100x + 2} = \frac 24[/tex]

Reduce the fractions

[tex]\frac{100y + 1}{100x + 2} = \frac 12[/tex]

Cross multiply

[tex]100x + 2 = 200y + 2[/tex]

Subtract 2 from both sides

[tex]100x = 200y[/tex]

Divide both sides by 100

[tex]x = 2y[/tex]

Recall that:

[tex]x + 2y = 500[/tex]

So, we have:

[tex]2y + 2y = 500[/tex]

[tex]4y=500[/tex]

Divide through by 4

[tex]y=125[/tex]

Recall that:

[tex]x = 2y[/tex]

So, we have:

[tex]x = 2 \times 125[/tex]

[tex]x = 250[/tex]

Also, we have:

[tex]U(x,y) = 100xy + x + 2y[/tex]

Substitute the values of x and y, in the above function

[tex]U(250,125) = 100 \times 250 \times 125 + 250 + 2 \times 125[/tex]

[tex]U(250,125) = 3125500[/tex]

Hence, the maximized value of the utility function is 3125500

Read more about utility functions at:

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