Question

Difficulty: EasyMatrices and Determinants

What is the determinant of the matrix P=(5327)P = \begin{pmatrix} 5 & 3 \\ 2 & 7 \end{pmatrix}?

Answer: 29

Answer

29
For a 2×22 \times 2 matrix (abcd)\begin{pmatrix} a & b \\ c & d \end{pmatrix}, the determinant is given by adbcad - bc. Substituting the values a=5a = 5, b=3b = 3, c=2c = 2, and d=7d = 7 yields (5×7)(3×2)=356=29(5 \times 7) - (3 \times 2) = 35 - 6 = 29.

Step-by-Step Solution

1
Identify the values of a,b,c,a, b, c, and dd from the given 2×22 \times 2 matrix P=(5327)P = \begin{pmatrix} 5 & 3 \\ 2 & 7 \end{pmatrix}.
a=5,b=3,c=2,d=7a = 5, b = 3, c = 2, d = 7
To set up the values for the 2×22 \times 2 determinant formula.
2
Multiply the elements of the main diagonal and the secondary diagonal.
Main diagonal product: 5×7=355 \times 7 = 35; Secondary diagonal product: 3×2=63 \times 2 = 6.
The determinant of a 2×22 \times 2 matrix is the difference between the main diagonal product and the secondary diagonal product.
3
Subtract the product of the secondary diagonal from the product of the main diagonal.
Determinant = 356=2935 - 6 = 29.
Completes the formula det(P)=adbc\det(P) = ad - bc.

Key Concept

Determinant of a 2x2 Matrix
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