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Let M and m respectively be the maximum and the minimum values of f (x) = left| beginarrayc c c 1 + sin^ 2 x & cos^ 2 x & 4 sin 4 x \\ sin^ 2 x & 1 + cos^ 2 x & 4 sin 4 x \\ sin^ 2 x & cos^ 2 x & 1 + 4 sin 4 x endarray right|, x in R Then mathbfM^4 -mathbfm^4 is equal to :

Solution & Explanation

### Related Formula sin^2 x + cos^2 x = 1 -1 le sin 4x le 1 ### Core Logic Apply the row operations R_2 to R_2 - R_1 and R_3 to R_3 - R_1 to simplify the determinant: f(x) = left| beginarrayc c c 1 + sin^ 2 x & cos^ 2 x & 4 sin 4 x \\ -1 & 1 & 0 \\ -1 & 0 & 1 endarray right| ### Step 1: Expand the Determinant Expanding along the first row: f(x) = (1 + sin^2 x)(1 - 0) - cos^2 x(-1 - 0) + 4sin 4x(0 - (-1)) f(x) = 1 + sin^2 x + cos^2 x + 4sin 4x Since sin^2 x + cos^2 x = 1, we get: f(x) = 2 + 4sin 4x ### Step 2: Find Maximum and Minimum Values The range of sin 4x is [-1, 1]. M = 2 + 4(1) = 6 m = 2 + 4(-1) = -2 ### Step 3: Calculate M^4 - m^4 M^4 - m^4 = 6^4 - (-2)^4 = 1296 - 16 = 1280 ### Pattern Recognition Look for repeated structures or cyclic additions in rows. Subtracting rows quickly creates zeros, reducing complex trigonometric matrices into elementary algebraic expressions. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Matrices and Determinants Class 11 Mathematics: Trigonometric Functions

Reference Study Guides

More Matrices and Determinants Previous-Year Questions — Page 3

Q69 2025 Determinant Properties of Adjoint
Let mathrmA = beginbmatrix 2 & 2 + mathrmp & 2 + mathrmp + mathrmq \\ 4 & 6 + 2mathrmp & 8 + 3mathrmp + 2mathrmq \\ 6 & 12 + 3mathrmp & 20 + 6mathrmp + 3mathrmq endbmatrix. If det left( adj(adj(3A)) right) = 2^m cdot 3^n, m, n in mathbbN, then m + n is equal to
  • A. 22
  • B. 24
  • C. 26
  • D. 20

Solution

### Related Formula |operatornameadj(operatornameadj(M))| = |M|^(n-1)^2 |kM| = k^n|M| ### Core Logic Perform determinant row reduction transforms to decouple tracking metrics p and q, leaving a baseline numerical determinant value behind. ### Step 1: Simplify the Determinant of Matrix A Execute columns adjustments: C_3 rightarrow C_3 - C_2 - C_1 times fracq2, then C_2 rightarrow C_2 - C_1 times left(1 + fracp2right): |A| = beginvmatrix 2 & 0 & 0 \\ 4 & 2 & 2+p \\ 6 & 6 & 8+3p endvmatrix = 2left(16 + 6p - 12 - 6pright) = 8 = 2^3 ### Step 2: Apply Adjoint Exponent Transforms For a matrix of dimensional profile size 3: |operatornameadj(operatornameadj(3A))| = |3A|^(3-1)^2 = |3A|^4 ### Step 3: Resolve Exponential System Size |3A| = 3^3 |A| = 3^3 times 2^3 |3A|^4 = (3^3 times 2^3)^4 = 2^12 times 3^12 Matching base parameter targets: m = 12, n = 12 implies m + n = 24 ### Pattern Recognition Linear parameter shifts down secondary column profiles usually dissolve cleanly during forward element elimination column steps. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Matrices and Determinants
Q61 2025 System of Linear Equations
Let alpha, beta ( alpha neq beta ) be the values of m, for which the equations x + y + z = 1 ; x + 2y + 4z = m and x + 4y + 10z = m^2 have infinitely many solutions. Then the value of sum_n=1^10 (n^alpha + n^beta) is equal to:
  • A. 440
  • B. 3080
  • C. 3410
  • D. 560

Solution

### Related Formula Cramer's rule for infinite solutions in a 3 variable system requires: Delta = Delta_x = Delta_y = Delta_z = 0 ### Core Logic Set up the primary matrix determinant Delta: Delta = beginvmatrix 1 & 1 & 1 \\ 1 & 2 & 4 \\ 1 & 4 & 10 endvmatrix = 1(20 - 16) - 1(10 - 4) + 1(4 - 2) = 4 - 6 + 2 = 0 Since Delta = 0 is true independent of m, analyze secondary delta constraints to maintain consistency for infinite paths. ### Step 1: Compute Dependent Variable Constraints Evaluate Delta_x = 0: Delta_x = beginvmatrix 1 & 1 & 1 \\ m & 2 & 4 \\ m^2 & 4 & 10 endvmatrix = 0 1(20 - 16) - 1(10m - 4m^2) + 1(4m - 2m^2) = 0 4 - 10m + 4m^2 + 4m - 2m^2 = 0 2m^2 - 6m + 4 = 0 implies m^2 - 3m + 2 = 0 Thus, m = 1, 2, which gives alpha = 1, beta = 2. ### Step 2: Calculate Sigma Expression sum_n=1^10 (n^1 + n^2) = sum_n=1^10 n + sum_n=1^10 n^2 = frac10(11)2 + frac10(11)(21)6 = 55 + 385 = 440 ### Pattern Recognition When infinitely many solutions are required, solving the determinant created by replacing one column with the constant vector provides parameter roots directly. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Matrices and Determinants
Q62 2025 Matrix Multiplication and Powers
Let mathbfA = [a_ij] be a matrix of order 3 times 3, with a_ij = left(sqrt2right)^i+j. If the sum of all the elements in the third row of A^2 is alpha + beta sqrt2, alpha, beta in mathbfZ, then alpha + beta is equal to
  • A. 280
  • B. 168
  • C. 210
  • D. 224

Solution

### Related Formula Element formula entry rule: a_ij = (sqrt2)^i+j ### Core Logic Constructing the initial matrix structure from the formula entries: A = beginbmatrix 2 & 2sqrt2 & 4 \\ 2sqrt2 & 4 & 4sqrt2 \\ 4 & 4sqrt2 & 8 endbmatrix Factoring scalar factor 4 out to ease squaring multiplication lines: A = 2beginbmatrix 1 & sqrt2 & 2 \\ sqrt2 & 2 & 2sqrt2 \\ 2 & 2sqrt2 & 4 endbmatrix ### Step 1: Calculate Rows of Power Matrix Squaring matrix A^2 matches scalar multipliers: A^2 = 4 beginbmatrix 1 & sqrt2 & 2 \\ sqrt2 & 2 & 2sqrt2 \\ 2 & 2sqrt2 & 4 endbmatrix beginbmatrix 1 & sqrt2 & 2 \\ sqrt2 & 2 & 2sqrt2 \\ 2 & 2sqrt2 & 4 endbmatrix Extract third row entries explicitly: textRow 3 = 4 beginbmatrix (2+4+8) & (2sqrt2+4sqrt2+8sqrt2) & (4+8+16) endbmatrix = 4 beginbmatrix 14 & 14sqrt2 & 28 endbmatrix ### Step 2: Aggregate Entries textSum of row elements = 4(14 + 14sqrt2 + 28) = 4(42 + 14sqrt2) = 168 + 56sqrt2 Matching structural parameters: alpha = 168, quad beta = 56 alpha + beta = 168 + 56 = 224 ### Pattern Recognition Pull common scaling scalar integers out of matrices before running large multiplications. It eliminates algebraic tracking errors across geometric indices. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Matrices and Determinants
Q71 2025 Symmetric and Skew Symmetric Matrices
Let M denote the set of all real matrices of order 3 times 3 and let S = \-3, -2, -1, 1, 2\. Let S_1 = left\A = left[ a_ij right] in M: A = A^T text and a_ij in S, forall i, j right\ S_2 = left\A = left[ a_ij right] in M: A = -A^T text and a_ij in S, forall i, j right\ S_3 = left\A = left[ a_ij right] in M: a_11 + a_22 + a_33 = 0 text and a_ij in S, forall i, j right\ If n(S_1 cup S_2 cup S_3) = 125alpha, then alpha equals.
Numerical Answer. Answer: 1613 to 1613

Solution

### Related Formula Set Principle of Inclusion-Exclusion: n(S_1 cup S_2 cup S_3) = n(S_1) + n(S_2) + n(S_3) - n(S_1 cap S_2) - n(S_2 cap S_3) - n(S_1 cap S_3) + n(S_1 cap S_2 cap S_3) ### Core Logic Let's count each subset based on the 5 elements available in S: 1. For S_1 (Symmetric matrices): 6 independent element choices implies n(S_1) = 5^6. 2. For S_2 (Skew-symmetric matrices): Diagonal elements must be 0, but 0 notin S, so n(S_2) = 0. Since n(S_2) = 0, any intersection term involving S_2 also becomes 0. ### Step 1: Calculating Trace Matrix Variations For S_3 (Trace equal to zero conditions): The condition a_11 + a_22 + a_33 = 0 over S = \-3, -2, -1, 1, 2\ has exactly 12 valid tuple combinations. The remaining 6 elements can be chosen freely. n(S_3) = 12 times 5^6 For the intersection n(S_1 cap S_3): n(S_1 cap S_3) = 12 times 5^3 ### Step 2: Final Inclusion-Exclusion Assembly n(S_1 cup S_2 cup S_3) = 5^6 + 12 times 5^6 - 12 times 5^3 = 5^3 times [13 times 5^3 - 12] = 125 times 1613 Thus, alpha = 1613. ### Pattern Recognition Always check if the set contains 0. Missing zero elements in skew-symmetric matrix setups instantly zeros out large blocks of permutations. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Matrices and Determinants
Q51 2025 Properties of Adjoint and Determinant
Let A be a matrix of order 3times3 and |A|=5[cite: 496]. If |2operatornameadj(3Aoperatornameadj(2A))|=2^alphacdot3^betacdot5^gamma, alpha, beta, gammain mathbbN [cite: 497], then alpha+beta+gamma is equal to [cite: 498]
  • A. 25
  • B. 26
  • C. 27
  • D. 28

Solution

### Related Formula For a matrix M of order ntimes n: 1. |kM| = k^n|M| 2. |operatornameadj(M)| = |M|^n-1 ### Core Logic Given n=3 and |A|=5[cite: 496]. Let us simplify the expression stepwise[cite: 1188]: |2operatornameadj(3Aoperatornameadj(2A))| = 2^3 cdot |operatornameadj(3Aoperatornameadj(2A))| [cite: 1188] Using the adjoint determinant rule [cite: 1188]: = 2^3 cdot |3Aoperatornameadj(2A)|^3-1 = 2^3 cdot |3Aoperatornameadj(2A)|^2 [cite: 1188] Now, apply the constant multiple property inside the determinant [cite: 1189]: = 2^3 cdot (3^3)^2 cdot |A|^2 cdot |operatornameadj(2A)|^2 [cite: 1189] = 2^3 cdot 3^6 cdot |A|^2 cdot (|2A|^3-1)^2 = 2^3 cdot 3^6 cdot |A|^2 cdot |2A|^4 [cite: 1190] Substitute |2A| = 2^3|A| [cite: 1191]: = 2^3 cdot 3^6 cdot |A|^2 cdot (2^3|A|)^4 = 2^3 cdot 3^6 cdot |A|^2 cdot 2^12 cdot |A|^4 [cite: 1191] = 2^15 cdot 3^6 cdot |A|^6 [cite: 1192] ### Step 1: Substituting the value of |A| Substitute |A|=5 into the simplified form [cite: 1193]: 2^15 cdot 3^6 cdot 5^6 = 2^alpha cdot 3^beta cdot 5^gamma [cite: 1193] Comparing exponents [cite: 1194]: alpha = 15, quad beta = 6, quad gamma = 6 [cite: 1194] Therefore, the sum is [cite: 1195]: alpha + beta + gamma = 15 + 6 + 6 = 27 [cite: 1195] ### Pattern Recognition Always evaluate scaling factor transformations from the outermost function inward. Keep absolute track of matrix dimensions as powers amplify rapidly with each step layer. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Matrices and Determinants

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