Mathematics, 24.11.2021 14:00 nicog94

Help me please. im in mental breakdown. i feel really down

Answers: 1

Show answers

Answers

Answer from: alexmarche8637

$\displaystyle A^{-1}=\left[\begin{array}{ccc}0.14&-0.10&0.22\\0.06&0.10&0.38\\0.26&0.10&-0.02\end{array}\right]$

Step-by-step explanation:

The inverse of matrix A is its adjoint divided by the determinant of A. That means the product of the adjoint and the original matrix is the determinant multiplied by the identity matrix. We can do some interesting things with that fact.

We can look at the off-diagonal elements of A·B and B·A. They should be zero in every case.

Element (1, 2) of A·B will be the dot product of row 1 of A and column 2 of B. That is ...

[7+a, -1, 3]·[5, a, -5] = 35 +5a -a -15 = 20 +4a = 4(a +5)

For this to be zero, we need a = -5.

Element (1, 2) of B·A will be the dot product of row 1 of B and column 2 of A. That is ...

[-7, 5, -11]·[-1, 16+b, 2] = 7 +5(16 +b) -22 = -15 +80 +5b = 5(b +13)

For this to be zero, we need b = -13.

We can find the determinant from element (1, 1) of B·A. That is the dot product of row 1 of B and column 1 of A:

[-7, 5, -11]·[7+a, a, 1] = -7(7 +a) +5a -11

For a = -5, this is ...

-7(7 -5) +5(-5) -11 = -14 -25 -11 = -50

So, the inverse of A is B/(-50):

$A^{-1}=\dfrac{B}{-50}=-\dfrac{1}{50}\left[\begin{array}{ccc}-7&5&-11\\-3&-5&-19\\-13&-5&1\end{array}\right] =\left[\begin{array}{ccc}0.14&-0.10&0.22\\0.06&0.10&0.38\\0.26&0.10&-0.02\end{array}\right]$

_____

Additional comment

It looks pretty simple here, but it took some playing around to find the simplicity of it. It's pretty easy to end up with 2nd-degree equations that are more difficult to solve and give extraneous answers.

Answer from: Quest

answer:

payment just for service

→

87.12

payment for service including tax

→

94.09

explanation:

service only with 20% tip

→

72.6

(

100

)

87.12

in the opening of the question the word 'service' is associated only with the pretax value.

the closing part of the question asks: how much did she pay for the

service

−−−−−−

so technically the answer is

→

72.6

(

100

)

87.12

however, the intention of the question provider may have been that your answer is to be

87.12

(

100

)

94.09

to 2 decimal places.

payment just for service

→

87.12

payment for service including tax

→

94.09

tony b

mar 21, 2017

answer:

trying to explain it another way

explanation:

service charge

→

72.60

20% tip

100

72.60

14.52

−−−−−−

←

add

87.12

tax

100

87.12

6.97

−−−−−

←

add

94.09

Another question on Mathematics

Mathematics, 21.06.2019 18:30

Tyler enjoys the fish so much that after his birthday his family decides to take him to a famous aquarium a tank at the aquarium is similar to his tank with the scale factor of 8 how many times greater is the volume of the tank at the aquarium than the volume of tyler tank

Answers: 2

Answer

Mathematics, 21.06.2019 20:30

This is about circle theorems. someone asap : (

Answers: 1

Answer

Mathematics, 21.06.2019 21:30

Ten members of balin's soccer team ran warm ups for practice. each member ran the same distance. their combined distance was 5/6 of a mile. to find the distance that each member ran, balin wrote the expression below.

Answers: 3

Answer

Mathematics, 22.06.2019 02:10

Triangle xyz, with vertices x(-2, 0), y(-2, -1), and z(-5, -2), undergoes a transformation to form triangle x′y′z′, with vertices x′(4, -2), y′(4, -3), and z′(1, -4). the type of transformation that triangle xyz undergoes is a . triangle x′y′z′ then undergoes a transformation to form triangle x′y′z′, with vertices x″(4, 2), y″(4, 3), and z″(1, 4). the type of transformation that triangle x′y′z′ undergoes is a .

Answers: 1

Answer

You know the right answer?

Help me please. im in mental breakdown. i feel really down
...

Questions