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Consider this matrix:

[[-4,2],[-6,6]]
Find the inverse of the matrix. Give exact values. Non-integers can be given as decimals or as simplified fractions.

Consider this matrix:\newline[4266] \left[\begin{array}{ll} -4 & 2 \\ -6 & 6 \end{array}\right] \newlineFind the inverse of the matrix. Give exact values. Non-integers can be given as decimals or as simplified fractions.

Full solution

Q. Consider this matrix:\newline[4266] \left[\begin{array}{ll} -4 & 2 \\ -6 & 6 \end{array}\right] \newlineFind the inverse of the matrix. Give exact values. Non-integers can be given as decimals or as simplified fractions.
  1. Write Matrix Determinant: Write down the matrix and its determinant.\newlineThe determinant of a 22x22 matrix [ab cd]\left[\begin{array}{cc}a & b \ c & d\end{array}\right] is adbcad - bc.\newlineFor the matrix [42 66]\left[\begin{array}{cc}-4 & 2 \ -6 & 6\end{array}\right], the determinant is (4)(6)(2)(6)(-4)(6) - (2)(-6).
  2. Calculate Determinant: Calculate the determinant.\newlineDeterminant = (4)(6)(2)(6)=24(12)=24+12=12(-4)(6) - (2)(-6) = -24 - (-12) = -24 + 12 = -12.
  3. Check Non-Zero Determinant: Check if the determinant is non-zero.\newlineSince the determinant is 12-12, which is non-zero, the matrix has an inverse.
  4. Inverse Matrix Formula: Write down the formula for the inverse of a 2×22 \times 2 matrix.\newlineThe inverse of a 2×22 \times 2 matrix [ab cd]\left[\begin{array}{cc} a & b \ c & d \end{array}\right] is 1determinant×[db ca]\frac{1}{\text{determinant}} \times \left[\begin{array}{cc} d & -b \ -c & a \end{array}\right].
  5. Apply Formula for Inverse: Apply the formula to find the inverse matrix. Using the determinant from Step 22 and the values from the original matrix, the inverse matrix is 1(12)\frac{1}{(-12)} * [62 64]\left[\begin{array}{cc} 6 & -2 \ 6 & -4 \end{array}\right].
  6. Multiply by Scalar: Multiply each element of the matrix by the scalar 1(12)\frac{1}{(-12)}. Inverse matrix = [(1(12))6(1(12))(2) (1(12))6(1(12))(4)]\left[\begin{array}{cc} \left(\frac{1}{(-12)}\right)\cdot 6 & \left(\frac{1}{(-12)}\right)\cdot (-2) \ \left(\frac{1}{(-12)}\right)\cdot 6 & \left(\frac{1}{(-12)}\right)\cdot (-4) \end{array}\right].
  7. Simplify Inverse Matrix: Simplify the matrix.\newlineInverse matrix = \left[\begin{array}{cc}\(\newline-\frac{1}{2} & \frac{1}{6} (\newline\)-\frac{1}{2} & \frac{1}{3}\newline\end{array}\right]\).
  8. Check Result with Identity: Check the result by multiplying the original matrix by the inverse matrix to see if it yields the identity matrix. Multiplying the original matrix by the inverse should give us the identity matrix if the inverse is correct.

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