Solve the Leontief production equation for an economy with three sectors, given that

\(C = \left[ {\begin{array}{*{20}{c}}{.2}&{.2}&{.0}\\{.3}&{.1}&{.3}\\{.1}&{.0}&{.2}\end{array}} \right]\)and \({\mathop{\rm d}\nolimits} = \left[ {\begin{array}{*{20}{c}}{40}\\{60}\\{80}\end{array}} \right]\).

Short Answer

Expert verified

\({\mathop{\rm x}\nolimits} = \left( {82.8,131.0,110.3} \right)\)

Step by step solution

01

Determine \(I - C\)

The Leontief input-output model or production equationis \(x = Cx + {\mathop{\rm d}\nolimits} \). The equation \(x = Cx + {\mathop{\rm d}\nolimits} \) can be written as \(I{\mathop{\rm x}\nolimits} - C{\mathop{\rm x}\nolimits} = {\mathop{\rm d}\nolimits} \) or \(\left( {I - C} \right){\mathop{\rm x}\nolimits} = {\mathop{\rm d}\nolimits} \).

\(\begin{array}{c}I - C = \left[ {\begin{array}{*{20}{c}}1&0&0\\0&1&0\\0&0&1\end{array}} \right] - \left[ {\begin{array}{*{20}{c}}{.2}&{.2}&{.0}\\{.3}&{.1}&{.3}\\{.1}&{.0}&{.2}\end{array}} \right]\\ = \left[ {\begin{array}{*{20}{c}}{.8}&{ - .2}&{.0}\\{ - .3}&{.9}&{ - .3}\\{ - .1}&{.0}&{.8}\end{array}} \right]\end{array}\)

02

Write the augmented matrix \(\left[ {\begin{array}{*{20}{c}}{I - C}&{\mathop{\rm d}\nolimits} \end{array}} \right]\)

It is given that \({\mathop{\rm d}\nolimits} = \left[ {\begin{array}{*{20}{c}}{40}\\{60}\\{80}\end{array}} \right]\).

The augmented matrix \(\left[ {\begin{array}{*{20}{c}}{I - C}&{\mathop{\rm d}\nolimits} \end{array}} \right]\) is shown below:

\(\left[ {\begin{array}{*{20}{c}}{.8}&{ - .2}&{.0}&{40.0}\\{ - .3}&{.9}&{ - .3}&{60.0}\\{ - .1}&{.0}&{.8}&{80.0}\end{array}} \right]\)

03

Apply the row operation

At row one, multiply row one by \(\frac{1}{{0.8}}\).

\( \sim \left[ {\begin{array}{*{20}{c}}1&{ - 0.25}&0&{50}\\{ - .3}&{.9}&{ - .3}&{60.0}\\{ - .1}&{.0}&{.8}&{80.0}\end{array}} \right]\)

At row two, multiply row one by 0.3 and add it to row two. At row three, multiply row one by 0.1 and add it to row three.

\( \sim \left[ {\begin{array}{*{20}{c}}1&{ - 0.25}&0&{50}\\0&{0.825}&{ - .3}&{75}\\0&{ - .025}&{.8}&{85}\end{array}} \right]\)

At row two, multiply row two by \(\frac{1}{{0.825}}\).

\( \sim \left[ {\begin{array}{*{20}{c}}1&{ - 0.25}&0&{50}\\0&1&{ - .3636}&{90.90}\\0&{ - .025}&{.8}&{85}\end{array}} \right]\)

At row one, multiply row two by 0.25 and add it to row one. At row three, multiply row two by 0.025 and add it to row three.

\( \sim \left[ {\begin{array}{*{20}{c}}1&0&{ - 0.0909}&{72.727}\\0&1&{ - 0.3636}&{90.90}\\0&0&{0.7909}&{87.272}\end{array}} \right]\)

At row three, multiply row three by 0.79090.

\( \sim \left[ {\begin{array}{*{20}{c}}1&0&{ - 0.0909}&{72.727}\\0&1&{ - 0.3636}&{90.90}\\0&0&1&{110.3448}\end{array}} \right]\)

At row one, multiply row three by 0.09090 and add it to row one.

\( \sim \left[ {\begin{array}{*{20}{c}}1&0&0&{82.7586}\\0&1&{ - 0.3636}&{90.90}\\0&0&1&{110.3448}\end{array}} \right]\)

At row two, multiply row three by 0.3636 and add it to row two.

\( \sim \left[ {\begin{array}{*{20}{c}}1&0&0&{82.7586}\\0&1&0&{131.03}\\0&0&1&{110.3448}\end{array}} \right]\)

Thus, \({\mathop{\rm x}\nolimits} = \left( {82.8,131.0,110.3} \right)\).

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Most popular questions from this chapter

Show that block upper triangular matrix \(A\) in Example 5is invertible if and only if both \({A_{{\bf{11}}}}\) and \({A_{{\bf{12}}}}\) are invertible. [Hint: If \({A_{{\bf{11}}}}\) and \({A_{{\bf{12}}}}\) are invertible, the formula for \({A^{ - {\bf{1}}}}\) given in Example 5 actually works as the inverse of \(A\).] This fact about \(A\) is an important part of several computer algorithims that estimates eigenvalues of matrices. Eigenvalues are discussed in chapter 5.

In Exercises 1–9, assume that the matrices are partitioned conformably for block multiplication. Compute the products shown in Exercises 1–4.

3. \[\left[ {\begin{array}{*{20}{c}}{\bf{0}}&I\\I&{\bf{0}}\end{array}} \right]\left[ {\begin{array}{*{20}{c}}W&X\\Y&Z\end{array}} \right]\]

Suppose \(\left( {B - C} \right)D = 0\), where Band Care \(m \times n\) matrices and \(D\) is invertible. Show that B = C.

Let \(A = \left( {\begin{aligned}{*{20}{c}}{\bf{1}}&{\bf{2}}\\{\bf{5}}&{{\bf{12}}}\end{aligned}} \right),{b_{\bf{1}}} = \left( {\begin{aligned}{*{20}{c}}{ - {\bf{1}}}\\{\bf{3}}\end{aligned}} \right),{b_{\bf{2}}} = \left( {\begin{aligned}{*{20}{c}}{\bf{1}}\\{ - {\bf{5}}}\end{aligned}} \right),{b_{\bf{3}}} = \left( {\begin{aligned}{*{20}{c}}{\bf{2}}\\{\bf{6}}\end{aligned}} \right),\) and \({b_{\bf{4}}} = \left( {\begin{aligned}{*{20}{c}}{\bf{3}}\\{\bf{5}}\end{aligned}} \right)\).

  1. Find \({A^{ - {\bf{1}}}}\), and use it to solve the four equations \(Ax = {b_{\bf{1}}},\)\(Ax = {b_2},\)\(Ax = {b_{\bf{3}}},\)\(Ax = {b_{\bf{4}}}\)\(\)
  2. The four equations in part (a) can be solved by the same set of row operations, since the coefficient matrix is the same in each case. Solve the four equations in part (a) by row reducing the augmented matrix \(\left( {\begin{aligned}{*{20}{c}}A&{{b_{\bf{1}}}}&{{b_{\bf{2}}}}&{{b_{\bf{3}}}}&{{b_{\bf{4}}}}\end{aligned}} \right)\).

In Exercises 1–9, assume that the matrices are partitioned conformably for block multiplication. Compute the products shown in Exercises 1–4.

2. \[\left[ {\begin{array}{*{20}{c}}E&{\bf{0}}\\{\bf{0}}&F\end{array}} \right]\left[ {\begin{array}{*{20}{c}}A&B\\C&D\end{array}} \right]\]

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