Algebra Examples
[-143112-10-1]
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
Step 3.1
Substitute [-143112-10-1] for A.
p(λ)=determinant([-143112-10-1]-λI3)
Step 3.2
Substitute [100010001] for I3.
p(λ)=determinant([-143112-10-1]-λ[100010001])
p(λ)=determinant([-143112-10-1]-λ[100010001])
Step 4
Step 4.1
Simplify each term.
Step 4.1.1
Multiply -λ by each element of the matrix.
p(λ)=determinant([-143112-10-1]+[-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2
Simplify each element in the matrix.
Step 4.1.2.1
Multiply -1 by 1.
p(λ)=determinant([-143112-10-1]+[-λ-λ⋅0-λ⋅0-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.2
Multiply -λ⋅0.
Step 4.1.2.2.1
Multiply 0 by -1.
p(λ)=determinant([-143112-10-1]+[-λ0λ-λ⋅0-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.2.2
Multiply 0 by λ.
p(λ)=determinant([-143112-10-1]+[-λ0-λ⋅0-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
p(λ)=determinant([-143112-10-1]+[-λ0-λ⋅0-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.3
Multiply -λ⋅0.
Step 4.1.2.3.1
Multiply 0 by -1.
p(λ)=determinant([-143112-10-1]+[-λ00λ-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.3.2
Multiply 0 by λ.
p(λ)=determinant([-143112-10-1]+[-λ00-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
p(λ)=determinant([-143112-10-1]+[-λ00-λ⋅0-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.4
Multiply -λ⋅0.
Step 4.1.2.4.1
Multiply 0 by -1.
p(λ)=determinant([-143112-10-1]+[-λ000λ-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.4.2
Multiply 0 by λ.
p(λ)=determinant([-143112-10-1]+[-λ000-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
p(λ)=determinant([-143112-10-1]+[-λ000-λ⋅1-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.5
Multiply -1 by 1.
p(λ)=determinant([-143112-10-1]+[-λ000-λ-λ⋅0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.6
Multiply -λ⋅0.
Step 4.1.2.6.1
Multiply 0 by -1.
p(λ)=determinant([-143112-10-1]+[-λ000-λ0λ-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.6.2
Multiply 0 by λ.
p(λ)=determinant([-143112-10-1]+[-λ000-λ0-λ⋅0-λ⋅0-λ⋅1])
p(λ)=determinant([-143112-10-1]+[-λ000-λ0-λ⋅0-λ⋅0-λ⋅1])
Step 4.1.2.7
Multiply -λ⋅0.
Step 4.1.2.7.1
Multiply 0 by -1.
p(λ)=determinant([-143112-10-1]+[-λ000-λ00λ-λ⋅0-λ⋅1])
Step 4.1.2.7.2
Multiply 0 by λ.
p(λ)=determinant([-143112-10-1]+[-λ000-λ00-λ⋅0-λ⋅1])
p(λ)=determinant([-143112-10-1]+[-λ000-λ00-λ⋅0-λ⋅1])
Step 4.1.2.8
Multiply -λ⋅0.
Step 4.1.2.8.1
Multiply 0 by -1.
p(λ)=determinant([-143112-10-1]+[-λ000-λ000λ-λ⋅1])
Step 4.1.2.8.2
Multiply 0 by λ.
p(λ)=determinant([-143112-10-1]+[-λ000-λ000-λ⋅1])
p(λ)=determinant([-143112-10-1]+[-λ000-λ000-λ⋅1])
Step 4.1.2.9
Multiply -1 by 1.
p(λ)=determinant([-143112-10-1]+[-λ000-λ000-λ])
p(λ)=determinant([-143112-10-1]+[-λ000-λ000-λ])
p(λ)=determinant([-143112-10-1]+[-λ000-λ000-λ])
Step 4.2
Add the corresponding elements.
p(λ)=determinant[-1-λ4+03+01+01-λ2+0-1+00+0-1-λ]
Step 4.3
Simplify each element.
Step 4.3.1
Add 4 and 0.
p(λ)=determinant[-1-λ43+01+01-λ2+0-1+00+0-1-λ]
Step 4.3.2
Add 3 and 0.
p(λ)=determinant[-1-λ431+01-λ2+0-1+00+0-1-λ]
Step 4.3.3
Add 1 and 0.
p(λ)=determinant[-1-λ4311-λ2+0-1+00+0-1-λ]
Step 4.3.4
Add 2 and 0.
p(λ)=determinant[-1-λ4311-λ2-1+00+0-1-λ]
Step 4.3.5
Add -1 and 0.
p(λ)=determinant[-1-λ4311-λ2-10+0-1-λ]
Step 4.3.6
Add 0 and 0.
p(λ)=determinant[-1-λ4311-λ2-10-1-λ]
p(λ)=determinant[-1-λ4311-λ2-10-1-λ]
p(λ)=determinant[-1-λ4311-λ2-10-1-λ]
Step 5
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 column 2 by its cofactor and add.
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 a12 is the determinant with row 1 and column 2 deleted.
|12-1-1-λ|
Step 5.1.4
Multiply element a12 by its cofactor.
-4|12-1-1-λ|
Step 5.1.5
The minor for a22 is the determinant with row 2 and column 2 deleted.
|-1-λ3-1-1-λ|
Step 5.1.6
Multiply element a22 by its cofactor.
(1-λ)|-1-λ3-1-1-λ|
Step 5.1.7
The minor for a32 is the determinant with row 3 and column 2 deleted.
|-1-λ312|
Step 5.1.8
Multiply element a32 by its cofactor.
0|-1-λ312|
Step 5.1.9
Add the terms together.
p(λ)=-4|12-1-1-λ|+(1-λ)|-1-λ3-1-1-λ|+0|-1-λ312|
p(λ)=-4|12-1-1-λ|+(1-λ)|-1-λ3-1-1-λ|+0|-1-λ312|
Step 5.2
Multiply 0 by |-1-λ312|.
p(λ)=-4|12-1-1-λ|+(1-λ)|-1-λ3-1-1-λ|+0
Step 5.3
Evaluate |12-1-1-λ|.
Step 5.3.1
The determinant of a 2×2 matrix can be found using the formula |abcd|=ad-cb.
p(λ)=-4(1(-1-λ)-(-1⋅2))+(1-λ)|-1-λ3-1-1-λ|+0
Step 5.3.2
Simplify the determinant.
Step 5.3.2.1
Simplify each term.
Step 5.3.2.1.1
Multiply -1-λ by 1.
p(λ)=-4(-1-λ-(-1⋅2))+(1-λ)|-1-λ3-1-1-λ|+0
Step 5.3.2.1.2
Multiply -(-1⋅2).
Step 5.3.2.1.2.1
Multiply -1 by 2.
p(λ)=-4(-1-λ--2)+(1-λ)|-1-λ3-1-1-λ|+0
Step 5.3.2.1.2.2
Multiply -1 by -2.
p(λ)=-4(-1-λ+2)+(1-λ)|-1-λ3-1-1-λ|+0
p(λ)=-4(-1-λ+2)+(1-λ)|-1-λ3-1-1-λ|+0
p(λ)=-4(-1-λ+2)+(1-λ)|-1-λ3-1-1-λ|+0
Step 5.3.2.2
Add -1 and 2.
p(λ)=-4(-λ+1)+(1-λ)|-1-λ3-1-1-λ|+0
p(λ)=-4(-λ+1)+(1-λ)|-1-λ3-1-1-λ|+0
p(λ)=-4(-λ+1)+(1-λ)|-1-λ3-1-1-λ|+0
Step 5.4
Evaluate |-1-λ3-1-1-λ|.
Step 5.4.1
The determinant of a 2×2 matrix can be found using the formula |abcd|=ad-cb.
p(λ)=-4(-λ+1)+(1-λ)((-1-λ)(-1-λ)-(-1⋅3))+0
Step 5.4.2
Simplify the determinant.
Step 5.4.2.1
Simplify each term.
Step 5.4.2.1.1
Expand (-1-λ)(-1-λ) using the FOIL Method.
Step 5.4.2.1.1.1
Apply the distributive property.
p(λ)=-4(-λ+1)+(1-λ)(-1(-1-λ)-λ(-1-λ)-(-1⋅3))+0
Step 5.4.2.1.1.2
Apply the distributive property.
p(λ)=-4(-λ+1)+(1-λ)(-1⋅-1-1(-λ)-λ(-1-λ)-(-1⋅3))+0
Step 5.4.2.1.1.3
Apply the distributive property.
p(λ)=-4(-λ+1)+(1-λ)(-1⋅-1-1(-λ)-λ⋅-1-λ(-λ)-(-1⋅3))+0
p(λ)=-4(-λ+1)+(1-λ)(-1⋅-1-1(-λ)-λ⋅-1-λ(-λ)-(-1⋅3))+0
Step 5.4.2.1.2
Simplify and combine like terms.
Step 5.4.2.1.2.1
Simplify each term.
Step 5.4.2.1.2.1.1
Multiply -1 by -1.
p(λ)=-4(-λ+1)+(1-λ)(1-1(-λ)-λ⋅-1-λ(-λ)-(-1⋅3))+0
Step 5.4.2.1.2.1.2
Multiply -1(-λ).
Step 5.4.2.1.2.1.2.1
Multiply -1 by -1.
p(λ)=-4(-λ+1)+(1-λ)(1+1λ-λ⋅-1-λ(-λ)-(-1⋅3))+0
Step 5.4.2.1.2.1.2.2
Multiply λ by 1.
p(λ)=-4(-λ+1)+(1-λ)(1+λ-λ⋅-1-λ(-λ)-(-1⋅3))+0
p(λ)=-4(-λ+1)+(1-λ)(1+λ-λ⋅-1-λ(-λ)-(-1⋅3))+0
Step 5.4.2.1.2.1.3
Multiply -λ⋅-1.
Step 5.4.2.1.2.1.3.1
Multiply -1 by -1.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+1λ-λ(-λ)-(-1⋅3))+0
Step 5.4.2.1.2.1.3.2
Multiply λ by 1.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ-λ(-λ)-(-1⋅3))+0
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ-λ(-λ)-(-1⋅3))+0
Step 5.4.2.1.2.1.4
Rewrite using the commutative property of multiplication.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ-1⋅-1λ⋅λ-(-1⋅3))+0
Step 5.4.2.1.2.1.5
Multiply λ by λ by adding the exponents.
Step 5.4.2.1.2.1.5.1
Move λ.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ-1⋅-1(λ⋅λ)-(-1⋅3))+0
Step 5.4.2.1.2.1.5.2
Multiply λ by λ.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ-1⋅-1λ2-(-1⋅3))+0
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ-1⋅-1λ2-(-1⋅3))+0
Step 5.4.2.1.2.1.6
Multiply -1 by -1.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ+1λ2-(-1⋅3))+0
Step 5.4.2.1.2.1.7
Multiply λ2 by 1.
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ+λ2-(-1⋅3))+0
p(λ)=-4(-λ+1)+(1-λ)(1+λ+λ+λ2-(-1⋅3))+0
Step 5.4.2.1.2.2
Add λ and λ.
p(λ)=-4(-λ+1)+(1-λ)(1+2λ+λ2-(-1⋅3))+0
p(λ)=-4(-λ+1)+(1-λ)(1+2λ+λ2-(-1⋅3))+0
Step 5.4.2.1.3
Multiply -(-1⋅3).
Step 5.4.2.1.3.1
Multiply -1 by 3.
p(λ)=-4(-λ+1)+(1-λ)(1+2λ+λ2--3)+0
Step 5.4.2.1.3.2
Multiply -1 by -3.
p(λ)=-4(-λ+1)+(1-λ)(1+2λ+λ2+3)+0
p(λ)=-4(-λ+1)+(1-λ)(1+2λ+λ2+3)+0
p(λ)=-4(-λ+1)+(1-λ)(1+2λ+λ2+3)+0
Step 5.4.2.2
Add 1 and 3.
p(λ)=-4(-λ+1)+(1-λ)(2λ+λ2+4)+0
Step 5.4.2.3
Reorder 2λ and λ2.
p(λ)=-4(-λ+1)+(1-λ)(λ2+2λ+4)+0
p(λ)=-4(-λ+1)+(1-λ)(λ2+2λ+4)+0
p(λ)=-4(-λ+1)+(1-λ)(λ2+2λ+4)+0
Step 5.5
Simplify the determinant.
Step 5.5.1
Add -4(-λ+1)+(1-λ)(λ2+2λ+4) and 0.
p(λ)=-4(-λ+1)+(1-λ)(λ2+2λ+4)
Step 5.5.2
Simplify each term.
Step 5.5.2.1
Apply the distributive property.
p(λ)=-4(-λ)-4⋅1+(1-λ)(λ2+2λ+4)
Step 5.5.2.2
Multiply -1 by -4.
p(λ)=4λ-4⋅1+(1-λ)(λ2+2λ+4)
Step 5.5.2.3
Multiply -4 by 1.
p(λ)=4λ-4+(1-λ)(λ2+2λ+4)
Step 5.5.2.4
Expand (1-λ)(λ2+2λ+4) by multiplying each term in the first expression by each term in the second expression.
p(λ)=4λ-4+1λ2+1(2λ)+1⋅4-λ⋅λ2-λ(2λ)-λ⋅4
Step 5.5.2.5
Simplify each term.
Step 5.5.2.5.1
Multiply λ2 by 1.
p(λ)=4λ-4+λ2+1(2λ)+1⋅4-λ⋅λ2-λ(2λ)-λ⋅4
Step 5.5.2.5.2
Multiply 2λ by 1.
p(λ)=4λ-4+λ2+2λ+1⋅4-λ⋅λ2-λ(2λ)-λ⋅4
Step 5.5.2.5.3
Multiply 4 by 1.
p(λ)=4λ-4+λ2+2λ+4-λ⋅λ2-λ(2λ)-λ⋅4
Step 5.5.2.5.4
Multiply λ by λ2 by adding the exponents.
Step 5.5.2.5.4.1
Move λ2.
p(λ)=4λ-4+λ2+2λ+4-(λ2λ)-λ(2λ)-λ⋅4
Step 5.5.2.5.4.2
Multiply λ2 by λ.
Step 5.5.2.5.4.2.1
Raise λ to the power of 1.
p(λ)=4λ-4+λ2+2λ+4-(λ2λ1)-λ(2λ)-λ⋅4
Step 5.5.2.5.4.2.2
Use the power rule aman=am+n to combine exponents.
p(λ)=4λ-4+λ2+2λ+4-λ2+1-λ(2λ)-λ⋅4
p(λ)=4λ-4+λ2+2λ+4-λ2+1-λ(2λ)-λ⋅4
Step 5.5.2.5.4.3
Add 2 and 1.
p(λ)=4λ-4+λ2+2λ+4-λ3-λ(2λ)-λ⋅4
p(λ)=4λ-4+λ2+2λ+4-λ3-λ(2λ)-λ⋅4
Step 5.5.2.5.5
Rewrite using the commutative property of multiplication.
p(λ)=4λ-4+λ2+2λ+4-λ3-1⋅2λ⋅λ-λ⋅4
Step 5.5.2.5.6
Multiply λ by λ by adding the exponents.
Step 5.5.2.5.6.1
Move λ.
p(λ)=4λ-4+λ2+2λ+4-λ3-1⋅2(λ⋅λ)-λ⋅4
Step 5.5.2.5.6.2
Multiply λ by λ.
p(λ)=4λ-4+λ2+2λ+4-λ3-1⋅2λ2-λ⋅4
p(λ)=4λ-4+λ2+2λ+4-λ3-1⋅2λ2-λ⋅4
Step 5.5.2.5.7
Multiply -1 by 2.
p(λ)=4λ-4+λ2+2λ+4-λ3-2λ2-λ⋅4
Step 5.5.2.5.8
Multiply 4 by -1.
p(λ)=4λ-4+λ2+2λ+4-λ3-2λ2-4λ
p(λ)=4λ-4+λ2+2λ+4-λ3-2λ2-4λ
Step 5.5.2.6
Subtract 2λ2 from λ2.
p(λ)=4λ-4-λ2+2λ+4-λ3-4λ
Step 5.5.2.7
Subtract 4λ from 2λ.
p(λ)=4λ-4-λ2-2λ+4-λ3
p(λ)=4λ-4-λ2-2λ+4-λ3
Step 5.5.3
Combine the opposite terms in 4λ-4-λ2-2λ+4-λ3.
Step 5.5.3.1
Add -4 and 4.
p(λ)=4λ-λ2-2λ+0-λ3
Step 5.5.3.2
Add 4λ-λ2-2λ and 0.
p(λ)=4λ-λ2-2λ-λ3
p(λ)=4λ-λ2-2λ-λ3
Step 5.5.4
Subtract 2λ from 4λ.
p(λ)=-λ2+2λ-λ3
Step 5.5.5
Move 2λ.
p(λ)=-λ2-λ3+2λ
Step 5.5.6
Reorder -λ2 and -λ3.
p(λ)=-λ3-λ2+2λ
p(λ)=-λ3-λ2+2λ
p(λ)=-λ3-λ2+2λ
Step 6
Set the characteristic polynomial equal to 0 to find the eigenvalues λ.
-λ3-λ2+2λ=0
Step 7
Step 7.1
Factor the left side of the equation.
Step 7.1.1
Factor -λ out of -λ3-λ2+2λ.
Step 7.1.1.1
Factor -λ out of -λ3.
-λ⋅λ2-λ2+2λ=0
Step 7.1.1.2
Factor -λ out of -λ2.
-λ⋅λ2-λ⋅λ+2λ=0
Step 7.1.1.3
Factor -λ out of 2λ.
-λ⋅λ2-λ⋅λ-λ⋅-2=0
Step 7.1.1.4
Factor -λ out of -λ(λ2)-λ(λ).
-λ(λ2+λ)-λ⋅-2=0
Step 7.1.1.5
Factor -λ out of -λ(λ2+λ)-λ(-2).
-λ(λ2+λ-2)=0
-λ(λ2+λ-2)=0
Step 7.1.2
Factor.
Step 7.1.2.1
Factor λ2+λ-2 using the AC method.
Step 7.1.2.1.1
Consider the form x2+bx+c. Find a pair of integers whose product is c and whose sum is b. In this case, whose product is -2 and whose sum is 1.
-1,2
Step 7.1.2.1.2
Write the factored form using these integers.
-λ((λ-1)(λ+2))=0
-λ((λ-1)(λ+2))=0
Step 7.1.2.2
Remove unnecessary parentheses.
-λ(λ-1)(λ+2)=0
-λ(λ-1)(λ+2)=0
-λ(λ-1)(λ+2)=0
Step 7.2
If any individual factor on the left side of the equation is equal to 0, the entire expression will be equal to 0.
λ=0
λ-1=0
λ+2=0
Step 7.3
Set λ equal to 0.
λ=0
Step 7.4
Set λ-1 equal to 0 and solve for λ.
Step 7.4.1
Set λ-1 equal to 0.
λ-1=0
Step 7.4.2
Add 1 to both sides of the equation.
λ=1
λ=1
Step 7.5
Set λ+2 equal to 0 and solve for λ.
Step 7.5.1
Set λ+2 equal to 0.
λ+2=0
Step 7.5.2
Subtract 2 from both sides of the equation.
λ=-2
λ=-2
Step 7.6
The final solution is all the values that make -λ(λ-1)(λ+2)=0 true.
λ=0,1,-2
λ=0,1,-2