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3 years ago

6

After a power failure, the temperature in a freezer increased at an average rate of 2.5 °F per hour. The total increase was 7.5

°F. Write and solve an equation to find the number of hours until the power was restored.

1 answer:

makvit [3.9K]3 years ago

6 0

YOU CAN WRITE AN EQUATION OF 7.5 Divide 2.5 = any letter

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Frank and Latoya each ran every day as part of an exercise routine. Frank ran

salantis [7]

3 miles each day for x days is 3x
5 miles each day for y days is 5y
Frank ran at least as many miles as Latoya is 3x >/= 5y

5 0

3 years ago

Find the? inverse, if it? exists, for the given matrix.<br><br> [4 3]<br><br> [3 6]

True [87]

Answer:

Therefore, the inverse of given matrix is

$=\begin{pmatrix}\frac{2}{5}&-\frac{1}{5}\\ -\frac{1}{5}&\frac{4}{15}\end{pmatrix}$

Step-by-step explanation:

The inverse of a square matrix $A$ is $A^{-1}$ such that

$A A^{-1}=I$ where I is the identity matrix.

Consider, $A = \left[\begin{array}{ccc}4&3\\3&6\end{array}\right]$

$\mathrm{Matrix\:can\:only\:be\:inverted\:if\:it\:is\:non-singular,\:that\:is:}$

$\det \begin{pmatrix}4&3 \\3&6\end{pmatrix}\ne 0$

$\mathrm{Find\:2x2\:matrix\:inverse\:according\:to\:the\:formula}:\quad \begin{pmatrix}a\:&\:b\:\\ c\:&\:d\:\end{pmatrix}^{-1}=\frac{1}{\det \begin{pmatrix}a\:&\:b\:\\ c\:&\:d\:\end{pmatrix}}\begin{pmatrix}d\:&\:-b\:\\ -c\:&\:a\:\end{pmatrix}$

$=\frac{1}{\det \begin{pmatrix}4&3\\ 3&6\end{pmatrix}}\begin{pmatrix}6&-3\\ -3&4\end{pmatrix}$

$\mathrm{Find\:the\:matrix\:determinant\:according\:to\:formula}:\quad \det \begin{pmatrix}a\:&\:b\:\\ c\:&\:d\:\end{pmatrix}\:=\:ad-bc$

$4\cdot \:6-3\cdot \:3=15$

$=\frac{1}{15}\begin{pmatrix}6&-3\\ -3&4\end{pmatrix}$

$=\begin{pmatrix}\frac{2}{5}&-\frac{1}{5}\\ -\frac{1}{5}&\frac{4}{15}\end{pmatrix}$

Therefore, the inverse of given matrix is

$=\begin{pmatrix}\frac{2}{5}&-\frac{1}{5}\\ -\frac{1}{5}&\frac{4}{15}\end{pmatrix}$

4 0

3 years ago

PLEASE HELP I POSTED LIKE 2 HOURS AGO WITH THIS QUESTION AND I NEED HELP:)

garik1379 [7]

A system is inconsistent when there are no solutions between the two equations. Graphically, the lines will be parallel (they never meet!) and the slopes will be the same. But the y-intercepts will be different.

Let's look at the four equations, with each solved as needed, into y = mx + b form.

A: 2x + y = 5

y = 5 - 2x

y = -2x + 5

Compared to y = 2x + 5, the slopes are different, so this system won't be inconsistent. Not a good choice.

B: y = 2x + 5

Compared to y = 2x + 5, the slopes are the same and the y intercepts are the same. This system has infinitely many solutions. Not a good choice.

C: 2x - 4y = 10

-4y = 10 - 2x

-4y = -2x + 10

y = 2/4x -10/4

Here the slopes are different, so, like A this is not a good choice.

D: 2y - 4x = -10

2y = =10 + 4x

2y = 4x - 10

y = 2x - 5

Compared to y = 2x + 5 we have the same slopes and different y intercepts. The lines will be parallel and the system is inconsistent.

Thus, D is the best choice.

7 0

3 years ago

Read 2 more answers

Please help <br><br> A. 13<br> B. 26<br> C. 40<br> D. 36<br> D. 41

Morgarella [4.7K]

The value of x is 26.

4 0

3 years ago

Read 2 more answers

At which vertex is the objective function C=3x-4y minimized

Oliga [24]

Options

(A) (9,0) (B) (-2,20) (C) (-5,2) (D) (0,-9)

Answer:

(B) (-2,20)

Step-by-step explanation:

Given the objective function, C=3x-4y

The vertex at which C is minimized will be the point (x,y) at which the expression gives the lowest value.

<u>Option A </u>

At (9,0), x=9, y=0

C=3(9)-4(0)=27-0

C=27

<u>Option B </u>

At (-2,20), x=-2, y=20

C=3(-2)-4(20)=-6-80

C=-86

<u>Option C</u>

At (-5,2), x=-5, y=2

C=3(-5)-4(2)=-15-8

C=-23

<u>Option D </u>

At (0,-9), x=0, y=-9

C=3(0)-4(-9)=0+36

C=36

The lowest value of C is -86. This occurs at the vertex (-2,20).

Therefore, the objective function C=3x-4y is minimized at (-2,20).

3 0

3 years ago