Plzzzzz help PLZZ asap!!!

In-s [12.5K]

ANSWER

24

EXPLANATION

For a matrix A of order n×n, the cofactor $C_{ij}$ of element $a_{ij}$ is defined to be

$C_{ij} = (-1)^{i+j} M_{ij}$

$M_{ij}$ is the minor of element $a_{ij}$ equal to the determinant of the matrix we get by taking matrix A and deleting row i and column j.

Here, we have

$C_{11} = (-1)^{1+1} M_{11} = M_{11}$

M₁₁ is the determinant of the matrix that is matrix A with row 1 and column 1 removed. The bold entries are the row and the column we delete.

$\begin{aligned} A=\begin{bmatrix} \bf 1 & \bf -6 & \bf -4\\ \bf 7 & 0 & -3 \\ \bf -9 & 8 & -8 \end{bmatrix} \implies M_{11} &= \text{det}\left(\begin{bmatrix} 0&-3 \\ 8&-8 \end{bmatrix} \right) \end{aligned}$

Since the determinant of a 2×2 matrix is

$\det\left( \begin{bmatrix} a & b \\ c& d \end{bmatrix} \right) = ad-bc$

it follows that

$\begin{aligned} A=\begin{bmatrix} \bf 1 & \bf -6 & \bf -4\\ \bf 7 & 0 & -3 \\ \bf -9 & 8 & -8 \end{bmatrix} \implies M_{11} &= \text{det}\left(\begin{bmatrix} 0&-3 \\ 8&-8 \end{bmatrix} \right) \\ &= (0)(-8) - (-3)(8) \\ &= -(-24) \\ &= 24 \end{aligned}$

so $C_{11} = M_{11} = 24$

4 0

3 years ago

Bob is looking at a helicopter that is flying 1,000 feet above the ground. Bob is 1500 feet from the helicopter. What angle of e

OverLord2011 [107]

I'm gonna send you a picture because it'll explain the answer better

6 0

3 years ago

Jillian measured the distance around a small fish pond as 27 yards. Which would be a good estimate for the distance across the p

DochEvi [55]

Assuming the fish pond is round, what you're given is the circumference.
So you know that 2<span>πr = 27.
We want to solve for the diameter, or d = 2r. We should isolate that.
2r = 27/</span><span>π
2r = 8.59 yards, or ~9 yards.</span>

3 0

3 years ago

A bag contains 5 blue marbles, 2black marbles ,and 3 red marbles. A marine is randomly drawn from the bag The probability of not

Juli2301 [7.4K]

<h3>Answers:</h3>

The probability of not drawing a red marble is 7/10

The probability of drawing a red marble is 3/10

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Explanation:

We have 3 red marbles out of 5+2+3 = 10 total. Therefore, the probability of selecting a red marble is 3/10.

The probability of not selecting a red marble is 7/10 because 3/10+7/10 = 1. Put another way, we have 7 marbles that aren't red (the 5 blue and 2 black ones) out of 10 total.

7 0

3 years ago

Which equation is graphed?

leonid [27]

Answer:

y= 2x+4

Step-by-step explanation:

To find slope its y2-y1/x2-x1

Plug it into any coordinate to get 2x

To find b in y=mx+b, you look at the y at the 0, in this case, "(0,4) Thefore the b is 5

5 0

3 years ago

Read 2 more answers