We read your photo as:

Given that A = [2 4; 3 6] and B = [11 3; 4 1] find C such that BC = A. 2. Find the inverse of the matrix [2 5; 3 4]. Hence or otherwise solve the equations 2x + 5y = 9 and 3x + 4y = 6.

Mathematics

ScanSolve AI Answer

Answers

2 parts
1

(−475737−27)\begin{pmatrix} -\frac{4}{7} & \frac{5}{7} \\ \frac{3}{7} & -\frac{2}{7} \end{pmatrix}

2

−67-\frac{6}{7}

157\frac{15}{7}

Step-by-step solution

5 steps

here are the solutions to the matrix problems:

1. Given that A=(2436)A = \begin{pmatrix} 2 & 4 \\ 3 & 6 \end{pmatrix} and B=(11341)B = \begin{pmatrix} 11 & 3 \\ 4 & 1 \end{pmatrix}, find CC such that B⋅C=AB \cdot C = A.

Step 1: To find CC, we need to multiply both sides of the equation B⋅C=AB \cdot C = A by the inverse of BB (B−1B^{-1}) from the left. This gives C=B−1⋅AC = B^{-1} \cdot A. First, calculate the determinant of BB.

det⁡(B)=(11)(1)−(3)(4)=11−12=−1\det(B) = (11)(1) - (3)(4) = 11 - 12 = -1

Step 2: Calculate the inverse of BB.

B−1=1det⁡(B)(1−3−411)=1−1(1−3−411)=(−134−11)B^{-1} = \frac{1}{\det(B)} \begin{pmatrix} 1 & -3 \\ -4 & 11 \end{pmatrix} = \frac{1}{-1} \begin{pmatrix} 1 & -3 \\ -4 & 11 \end{pmatrix} = \begin{pmatrix} -1 & 3 \\ 4 & -11 \end{pmatrix}

Step 3: Multiply B−1B^{-1} by AA to find CC.

C=B−1⋅A=(−134−11)(2436)C = B^{-1} \cdot A = \begin{pmatrix} -1 & 3 \\ 4 & -11 \end{pmatrix} \begin{pmatrix} 2 & 4 \\ 3 & 6 \end{pmatrix} C=((−1)(2)+(3)(3)(−1)(4)+(3)(6)(4)(2)+(−11)(3)(4)(4)+(−11)(6))C = \begin{pmatrix} (-1)(2) + (3)(3) & (-1)(4) + (3)(6) \\ (4)(2) + (-11)(3) & (4)(4) + (-11)(6) \end{pmatrix} C=(−2+9−4+188−3316−66)C = \begin{pmatrix} -2 + 9 & -4 + 18 \\ 8 - 33 & 16 - 66 \end{pmatrix} C=(714−25−50)C = \begin{pmatrix} 7 & 14 \\ -25 & -50 \end{pmatrix}

The matrix CC is (714−25−50)\boxed{\begin{pmatrix} 7 & 14 \\ -25 & -50 \end{pmatrix}}.

2. Find the inverse of the matrix (2534)\begin{pmatrix} 2 & 5 \\ 3 & 4 \end{pmatrix}. Hence or otherwise solve the equations 2x+5y=92x + 5y = 9 and 3x+4y=63x + 4y = 6.

Part 1· 2 steps

Find the inverse of the matrix.

  1. Let the given matrix be M=(2534)M = \begin{pmatrix} 2 & 5 \\ 3 & 4 \end{pmatrix}.

    First, calculate the determinant of MM.

    det⁡(M)=(2)(4)−(5)(3)=8−15=−7\det(M) = (2)(4) - (5)(3) = 8 - 15 = -7
  2. Calculate the inverse of MM.

    M−1=1det⁡(M)(4−5−32)=1−7(4−5−32)=(−475737−27)M^{-1} = \frac{1}{\det(M)} \begin{pmatrix} 4 & -5 \\ -3 & 2 \end{pmatrix} = \frac{1}{-7} \begin{pmatrix} 4 & -5 \\ -3 & 2 \end{pmatrix} = \begin{pmatrix} -\frac{4}{7} & \frac{5}{7} \\ \frac{3}{7} & -\frac{2}{7} \end{pmatrix}

    The inverse of the matrix is (−475737−27)\boxed{\begin{pmatrix} -\frac{4}{7} & \frac{5}{7} \\ \frac{3}{7} & -\frac{2}{7} \end{pmatrix}}.

Part 2

−67-\frac{6}{7}

Solve the equations using the inverse matrix.

  1. Write the system of equations in matrix form.

    (2534)(xy)=(96)\begin{pmatrix} 2 & 5 \\ 3 & 4 \end{pmatrix} \begin{pmatrix} x \\ y \end{pmatrix} = \begin{pmatrix} 9 \\ 6 \end{pmatrix}
  2. Multiply both sides by the inverse matrix M−1M^{-1} found in Part 1.

    (xy)=M−1(96)=(−475737−27)(96)\begin{pmatrix} x \\ y \end{pmatrix} = M^{-1} \begin{pmatrix} 9 \\ 6 \end{pmatrix} = \begin{pmatrix} -\frac{4}{7} & \frac{5}{7} \\ \frac{3}{7} & -\frac{2}{7} \end{pmatrix} \begin{pmatrix} 9 \\ 6 \end{pmatrix}
  3. Perform the matrix multiplication.

    (xy)=((−47)(9)+(57)(6)(37)(9)+(−27)(6))\begin{pmatrix} x \\ y \end{pmatrix} = \begin{pmatrix} (-\frac{4}{7})(9) + (\frac{5}{7})(6) \\ (\frac{3}{7})(9) + (-\frac{2}{7})(6) \end{pmatrix} (xy)=(−367+307277−127)\begin{pmatrix} x \\ y \end{pmatrix} = \begin{pmatrix} -\frac{36}{7} + \frac{30}{7} \\ \frac{27}{7} - \frac{12}{7} \end{pmatrix} (xy)=(−67157)\begin{pmatrix} x \\ y \end{pmatrix} = \begin{pmatrix} -\frac{6}{7} \\ \frac{15}{7} \end{pmatrix}

    The solution to the equations is x=−67x = \boxed{-\frac{6}{7}} and y=157y = \boxed{\frac{15}{7}}.

Was this helpful?

Try one yourself

A new problem that tests the same skill.

Still stuck on this one?

Ask a follow-up, and the answer starts from this question.

Got a different question?Ask your own question
Handwritten step-by-step solution preview

Handwritten Step-by-Step Solution

Get this as a handwritten image on WhatsApp — like a tutor wrote it for you.

Try on WhatsApp