Finite Math Examples

Find the Eigenvalues [[0,0.1,0.9],[0.6,0,0.4],[0.9,0.1,0]]
[00.10.90.600.40.90.10]00.10.90.600.40.90.10
Step 1
Set up the formula to find the characteristic equation p(λ).
p(λ)=determinant(A-λI3)
Step 2
The identity matrix or unit matrix of size 3 is the 3×3 square matrix with ones on the main diagonal and zeros elsewhere.
[100010001]
Step 3
Substitute the known values into p(λ)=determinant(A-λI3).
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Step 3.1
Substitute [00.10.90.600.40.90.10] for A.
p(λ)=determinant([00.10.90.600.40.90.10]-λI3)
Step 3.2
Substitute [100010001] for I3.
p(λ)=determinant([00.10.90.600.40.90.10]-λ[100010001])
p(λ)=determinant([00.10.90.600.40.90.10]-λ[100010001])
Step 4
Simplify.
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Step 4.1
Simplify each term.
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Step 4.1.1
Multiply -λ by each element of the matrix.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ1-λ0-λ0-λ0-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2
Simplify each element in the matrix.
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Step 4.1.2.1
Multiply -1 by 1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ-λ0-λ0-λ0-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.2
Multiply -λ0.
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Step 4.1.2.2.1
Multiply 0 by -1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ0λ-λ0-λ0-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.2.2
Multiply 0 by λ.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ0-λ0-λ0-λ1-λ0-λ0-λ0-λ1])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ0-λ0-λ0-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.3
Multiply -λ0.
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Step 4.1.2.3.1
Multiply 0 by -1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ00λ-λ0-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.3.2
Multiply 0 by λ.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ00-λ0-λ1-λ0-λ0-λ0-λ1])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ00-λ0-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.4
Multiply -λ0.
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Step 4.1.2.4.1
Multiply 0 by -1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000λ-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.4.2
Multiply 0 by λ.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ1-λ0-λ0-λ0-λ1])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ1-λ0-λ0-λ0-λ1])
Step 4.1.2.5
Multiply -1 by 1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ-λ0-λ0-λ0-λ1])
Step 4.1.2.6
Multiply -λ0.
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Step 4.1.2.6.1
Multiply 0 by -1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ0λ-λ0-λ0-λ1])
Step 4.1.2.6.2
Multiply 0 by λ.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ0-λ0-λ0-λ1])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ0-λ0-λ0-λ1])
Step 4.1.2.7
Multiply -λ0.
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Step 4.1.2.7.1
Multiply 0 by -1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ00λ-λ0-λ1])
Step 4.1.2.7.2
Multiply 0 by λ.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ00-λ0-λ1])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ00-λ0-λ1])
Step 4.1.2.8
Multiply -λ0.
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Step 4.1.2.8.1
Multiply 0 by -1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ000λ-λ1])
Step 4.1.2.8.2
Multiply 0 by λ.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ000-λ1])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ000-λ1])
Step 4.1.2.9
Multiply -1 by 1.
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ000-λ])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ000-λ])
p(λ)=determinant([00.10.90.600.40.90.10]+[-λ000-λ000-λ])
Step 4.2
Add the corresponding elements.
p(λ)=determinant[0-λ0.1+00.9+00.6+00-λ0.4+00.9+00.1+00-λ]
Step 4.3
Simplify each element.
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Step 4.3.1
Subtract λ from 0.
p(λ)=determinant[-λ0.1+00.9+00.6+00-λ0.4+00.9+00.1+00-λ]
Step 4.3.2
Add 0.1 and 0.
p(λ)=determinant[-λ0.10.9+00.6+00-λ0.4+00.9+00.1+00-λ]
Step 4.3.3
Add 0.9 and 0.
p(λ)=determinant[-λ0.10.90.6+00-λ0.4+00.9+00.1+00-λ]
Step 4.3.4
Add 0.6 and 0.
p(λ)=determinant[-λ0.10.90.60-λ0.4+00.9+00.1+00-λ]
Step 4.3.5
Subtract λ from 0.
p(λ)=determinant[-λ0.10.90.6-λ0.4+00.9+00.1+00-λ]
Step 4.3.6
Add 0.4 and 0.
p(λ)=determinant[-λ0.10.90.6-λ0.40.9+00.1+00-λ]
Step 4.3.7
Add 0.9 and 0.
p(λ)=determinant[-λ0.10.90.6-λ0.40.90.1+00-λ]
Step 4.3.8
Add 0.1 and 0.
p(λ)=determinant[-λ0.10.90.6-λ0.40.90.10-λ]
Step 4.3.9
Subtract λ from 0.
p(λ)=determinant[-λ0.10.90.6-λ0.40.90.1-λ]
p(λ)=determinant[-λ0.10.90.6-λ0.40.90.1-λ]
p(λ)=determinant[-λ0.10.90.6-λ0.40.90.1-λ]
Step 5
Find the determinant.
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Step 5.1
Choose the row or column with the most 0 elements. If there are no 0 elements choose any row or column. Multiply every element in row 1 by its cofactor and add.
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Step 5.1.1
Consider the corresponding sign chart.
|+-+-+-+-+|
Step 5.1.2
The cofactor is the minor with the sign changed if the indices match a - position on the sign chart.
Step 5.1.3
The minor for a11 is the determinant with row 1 and column 1 deleted.
|-λ0.40.1-λ|
Step 5.1.4
Multiply element a11 by its cofactor.
-λ|-λ0.40.1-λ|
Step 5.1.5
The minor for a12 is the determinant with row 1 and column 2 deleted.
|0.60.40.9-λ|
Step 5.1.6
Multiply element a12 by its cofactor.
-0.1|0.60.40.9-λ|
Step 5.1.7
The minor for a13 is the determinant with row 1 and column 3 deleted.
|0.6-λ0.90.1|
Step 5.1.8
Multiply element a13 by its cofactor.
0.9|0.6-λ0.90.1|
Step 5.1.9
Add the terms together.
p(λ)=-λ|-λ0.40.1-λ|-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
p(λ)=-λ|-λ0.40.1-λ|-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2
Evaluate |-λ0.40.1-λ|.
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Step 5.2.1
The determinant of a 2×2 matrix can be found using the formula |abcd|=ad-cb.
p(λ)=-λ(-λ(-λ)-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2.2
Simplify each term.
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Step 5.2.2.1
Rewrite using the commutative property of multiplication.
p(λ)=-λ(-1-1λλ-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2.2.2
Multiply λ by λ by adding the exponents.
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Step 5.2.2.2.1
Move λ.
p(λ)=-λ(-1-1(λλ)-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2.2.2.2
Multiply λ by λ.
p(λ)=-λ(-1-1λ2-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
p(λ)=-λ(-1-1λ2-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2.2.3
Multiply -1 by -1.
p(λ)=-λ(1λ2-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2.2.4
Multiply λ2 by 1.
p(λ)=-λ(λ2-0.10.4)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.2.2.5
Multiply -0.1 by 0.4.
p(λ)=-λ(λ2-0.04)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
p(λ)=-λ(λ2-0.04)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
p(λ)=-λ(λ2-0.04)-0.1|0.60.40.9-λ|+0.9|0.6-λ0.90.1|
Step 5.3
Evaluate |0.60.40.9-λ|.
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Step 5.3.1
The determinant of a 2×2 matrix can be found using the formula |abcd|=ad-cb.
p(λ)=-λ(λ2-0.04)-0.1(0.6(-λ)-0.90.4)+0.9|0.6-λ0.90.1|
Step 5.3.2
Simplify each term.
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Step 5.3.2.1
Multiply -1 by 0.6.
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.90.4)+0.9|0.6-λ0.90.1|
Step 5.3.2.2
Multiply -0.9 by 0.4.
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9|0.6-λ0.90.1|
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9|0.6-λ0.90.1|
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9|0.6-λ0.90.1|
Step 5.4
Evaluate |0.6-λ0.90.1|.
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Step 5.4.1
The determinant of a 2×2 matrix can be found using the formula |abcd|=ad-cb.
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.60.1-0.9(-λ))
Step 5.4.2
Simplify the determinant.
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Step 5.4.2.1
Simplify each term.
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Step 5.4.2.1.1
Multiply 0.6 by 0.1.
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.06-0.9(-λ))
Step 5.4.2.1.2
Multiply -1 by -0.9.
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.06+0.9λ)
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.06+0.9λ)
Step 5.4.2.2
Reorder 0.06 and 0.9λ.
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
p(λ)=-λ(λ2-0.04)-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5
Simplify the determinant.
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Step 5.5.1
Simplify each term.
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Step 5.5.1.1
Apply the distributive property.
p(λ)=-λλ2-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5.1.2
Multiply λ by λ2 by adding the exponents.
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Step 5.5.1.2.1
Move λ2.
p(λ)=-(λ2λ)-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5.1.2.2
Multiply λ2 by λ.
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Step 5.5.1.2.2.1
Raise λ to the power of 1.
p(λ)=-(λ2λ1)-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5.1.2.2.2
Use the power rule aman=am+n to combine exponents.
p(λ)=-λ2+1-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
p(λ)=-λ2+1-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5.1.2.3
Add 2 and 1.
p(λ)=-λ3-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
p(λ)=-λ3-λ-0.04-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5.1.3
Multiply -0.04 by -1.
p(λ)=-λ3+0.04λ-0.1(-0.6λ-0.36)+0.9(0.9λ+0.06)
Step 5.5.1.4
Apply the distributive property.
p(λ)=-λ3+0.04λ-0.1(-0.6λ)-0.1-0.36+0.9(0.9λ+0.06)
Step 5.5.1.5
Multiply -0.6 by -0.1.
p(λ)=-λ3+0.04λ+0.06λ-0.1-0.36+0.9(0.9λ+0.06)
Step 5.5.1.6
Multiply -0.1 by -0.36.
p(λ)=-λ3+0.04λ+0.06λ+0.036+0.9(0.9λ+0.06)
Step 5.5.1.7
Apply the distributive property.
p(λ)=-λ3+0.04λ+0.06λ+0.036+0.9(0.9λ)+0.90.06
Step 5.5.1.8
Multiply 0.9 by 0.9.
p(λ)=-λ3+0.04λ+0.06λ+0.036+0.81λ+0.90.06
Step 5.5.1.9
Multiply 0.9 by 0.06.
p(λ)=-λ3+0.04λ+0.06λ+0.036+0.81λ+0.054
p(λ)=-λ3+0.04λ+0.06λ+0.036+0.81λ+0.054
Step 5.5.2
Add 0.04λ and 0.06λ.
p(λ)=-λ3+0.1λ+0.036+0.81λ+0.054
Step 5.5.3
Add 0.1λ and 0.81λ.
p(λ)=-λ3+0.91λ+0.036+0.054
Step 5.5.4
Add 0.036 and 0.054.
p(λ)=-λ3+0.91λ+0.09
p(λ)=-λ3+0.91λ+0.09
p(λ)=-λ3+0.91λ+0.09
Step 6
Set the characteristic polynomial equal to 0 to find the eigenvalues λ.
-λ3+0.91λ+0.09=0
Step 7
Solve for λ.
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Step 7.1
Graph each side of the equation. The solution is the x-value of the point of intersection.
λ-0.9,-0.1,1
λ-0.9,-0.1,1
 [x2  12  π  xdx ]