Mastering Algebra: Your Gateway to Success
Problem:
Consider the matrices \(A = \begin{bmatrix} 2 & 4 \\ 1 & 3 \end{bmatrix}\) and \(B = \begin{bmatrix} 1 & 2 \\ 3 & 5 \end{bmatrix}\). Compute the product \(AB\) and find its eigenvalues.
Solution:
To find the product \(AB\), multiply the matrices element-wise and sum the results. The result is:
\[ AB = \begin{bmatrix} 2(1) + 4(3) & 2(2) + 4(5) \\ 1(1) + 3(3) & 1(2) + 3(5) \end{bmatrix} = \begin{bmatrix} 14 & 22 \\ 10 & 17 \end{bmatrix} \]
To find the eigenvalues, solve the characteristic equation \(|AB - \lambda I| = 0\), where \(I\) is the identity matrix. The eigenvalues for this matrix are \(\lambda_1 \approx 20.33\) and \(\lambda_2 \approx 10.67\).
Question 2: Abstract Algebra - Group Theory
Problem:
Let \(G\) be a group with operation \(\ast\) defined by \(a \ast b = ab - a - b\). Prove that \(G\) is an abelian group.
Solution:
To prove that \(G\) is an abelian group, we need to show that for all elements \(a, b \in G\), \(a \ast b = b \ast a\). Using the given operation:
\[ a \ast b = ab - a - b \]
\[ b \ast a = ba - b - a \]
Now, we need to show that \(ab - a - b = ba - b - a\). Simplifying both sides, we find that they are indeed equal. Therefore, \(G\) is an abelian group.
Question 3: Polynomial Rings - Factorization
Problem:
Factorize the polynomial \(f(x) = x^3 - 6x^2 + 11x - 6\) over the field of real numbers.
Solution:
To factorize \(f(x)\), we can use synthetic division or factor theorem to find the roots. The roots of the polynomial are \(x = 1\) and \(x = 2\). Therefore, the factorization is:
\[ f(x) = (x - 1)(x - 2)(x - 3) \]
Question 4: Linear Programming - Optimization
Problem:
A company produces two products, A and B. The profit per unit for product A is $5, and for product B is $8. The company has a constraint on the raw material, with a maximum of 100 units available. Formulate the linear programming problem to maximize the profit.
Solution:
Let \(x\) be the number of units of product A and \(y\) be the number of units of product B. The objective function to maximize is \(Z = 5x + 8y\), subject to the constraint \(x + y \leq 100\). The variables \(x\) and \(y\) are non-negative.
Question 5: Ring Theory - Ideals
Problem:
Let \(R\) be a commutative ring with identity, and let \(I\) be an ideal of \(R\). Prove that the quotient ring \(R/I\) is also a commutative ring.
Solution:
To prove that \(R/I\) is a commutative ring, we need to show that for all elements \(a + I, b + I \in R/I\), \((a + I)(b + I) = (b + I)(a + I)\). The multiplication in \(R/I\) is defined as \((a + I)(b + I) = ab + I\). Using this definition, we can show that \(ab + I = ba + I\), proving that \(R/I\) is a commutative ring.
Thanks for the solution
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