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lyudmila [28]
2 years ago
8

Marcus earns money from feeding cats and answering emails. He earns $7 a week for each cat he feeds and $0.20 for each email he

answers. Marcus answered 140 emails and earned $49 last week. Part A: Create an equation that will determine the number of cats he fed. (3 points) Part B: Solve this equation justifying each step with an algebraic property of equality. (6 points) Part C: How many cats did Marcus feed last week?
Mathematics
2 answers:
IgorC [24]2 years ago
6 0
Part A: 7c + 0.20(140) = $49Part B :  7c + 0.20(140) = $490.2*140 = 287c+28=4949-28=217c=217/7 = 0    7/21=3Part C: C=3 cats fed
KengaRu [80]2 years ago
4 0
28 dollars in emails so 3 cats were fed 7 x 3 =21 and 21 was the other half of money he made i don't know c sry
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Find c1 and c2 such that M2+c1M+c2I2=0, where I2 is the identity 2×2 matrix and 0 is the zero matrix of appropriate dimension.
Katyanochek1 [597]

The question is missing parts. Here is the complete question.

Let M = \left[\begin{array}{cc}6&5\\-1&-4\end{array}\right]. Find c_{1} and c_{2} such that M^{2}+c_{1}M+c_{2}I_{2}=0, where I_{2} is the identity 2x2 matrix and 0 is the zero matrix of appropriate dimension.

Answer: c_{1} = \frac{-16}{10}

             c_{2}=\frac{-214}{10}

Step-by-step explanation: Identity matrix is a sqaure matrix that has 1's along the main diagonal and 0 everywhere else. So, a 2x2 identity matrix is:

\left[\begin{array}{cc}1&0\\0&1\end{array}\right]

M^{2} = \left[\begin{array}{cc}6&5\\-1&-4\end{array}\right]\left[\begin{array}{cc}6&5\\-1&-4\end{array}\right]

M^{2}=\left[\begin{array}{cc}31&10\\-2&15\end{array}\right]

Solving equation:

\left[\begin{array}{cc}31&10\\-2&15\end{array}\right]+c_{1}\left[\begin{array}{cc}6&5\\-1&-4\end{array}\right] +c_{2}\left[\begin{array}{cc}1&0\\0&1\end{array}\right] =\left[\begin{array}{cc}0&0\\0&0\end{array}\right]

Multiplying a matrix and a scalar results in all the terms of the matrix multiplied by the scalar. You can only add matrices of the same dimensions.

So, the equation is:

\left[\begin{array}{cc}31&10\\-2&15\end{array}\right]+\left[\begin{array}{cc}6c_{1}&5c_{1}\\-1c_{1}&-4c_{1}\end{array}\right] +\left[\begin{array}{cc}c_{2}&0\\0&c_{2}\end{array}\right] =\left[\begin{array}{cc}0&0\\0&0\end{array}\right]

And the system of equations is:

6c_{1}+c_{2} = -31\\-4c_{1}+c_{2} = -15

There are several methods to solve this system. One of them is to multiply the second equation to -1 and add both equations:

6c_{1}+c_{2} = -31\\(-1)*-4c_{1}+c_{2} = -15*(-1)

6c_{1}+c_{2} = -31\\4c_{1}-c_{2} = 15

10c_{1} = -16

c_{1} = \frac{-16}{10}

With c_{1}, substitute in one of the equations and find c_{2}:

6c_{1}+c_{2}=-31

c_{2}=-31-6(\frac{-16}{10} )

c_{2}=-31+(\frac{96}{10} )

c_{2}=\frac{-310+96}{10}

c_{2}=\frac{-214}{10}

<u>For the equation, </u>c_{1} = \frac{-16}{10}<u> and </u>c_{2}=\frac{-214}{10}<u />

6 0
1 year ago
Find, correct to the nearest degree, the three angles of the triangle with the vertices d(0,1,1), e( 2, 4,3) − , and f(1, 2, 1)
Ksju [112]
Well, here's one way to do it at least... 

<span>For reference, let 'a' be the side opposite A (segment BC), 'b' be the side opposite B (segment AC) and 'c' be the side opposite C (segment AB). </span>

<span>Let P=(4,0) be the projection of B onto the x-axis. </span>
<span>Let Q=(-3,0) be the projection of C onto the x-axis. </span>

<span>Look at the angle QAC. It has tangent = 5/4 (do you see why?), so angle A is atan(5/4). </span>

<span>Likewise, angle PAB has tangent = 6/3 = 2, so angle PAB is atan(2). </span>

<span>Angle A, then, is 180 - atan(5/4) - atan(2) = 65.225. One down, two to go. </span>

<span>||b|| = sqrt(41) (use Pythagorian Theorum on triangle AQC) </span>
<span>||c|| = sqrt(45) (use Pythagorian Theorum on triangle APB) </span>

<span>Using the Law of Cosines... </span>
<span>||a||^2 = ||b||^2 + ||c||^2 - 2(||b||)(||c||)cos(A) </span>
<span>||a||^2 = 41 + 45 - 2(sqrt(41))(sqrt(45))(.4191) </span>
<span>||a||^2 = 86 - 36 </span>
<span>||a||^2 = 50 </span>
<span>||a|| = sqrt(50) </span>

<span>Now apply the Law of Sines to find the other two angles. </span>

<span>||b|| / sin(B) = ||a|| / sin(A) </span>
<span>sqrt(41) / sin(B) = sqrt(50) / .9080 </span>
<span>(.9080)sqrt(41) / sqrt(50) = sin(B) </span>
<span>.8222 = sin(B) </span>
<span>asin(.8222) = B </span>
<span>55.305 = B </span>

<span>Two down, one to go... </span>

<span>||c|| / sin(C) = ||a|| / sin(A) </span>
<span>sqrt(45) / sin(C) = sqrt(50) / .9080 </span>
<span>(.9080)sqrt(45) / sqrt(50) = sin(C) </span>
<span>.8614 = sin(C) </span>
<span>asin(.8614) = C </span>
<span>59.470 = C </span>

<span>So your three angles are: </span>

<span>A = 65.225 </span>
<span>B = 55.305 </span>
<span>C = 59.470 </span>
8 0
1 year ago
Isabel wrote this mystery problem: The quotient is a multiple of 6. The dividend is a multiple of 9. The divisor is s factor of
8090 [49]

Answer: 18

Step-by-step explanation: well 9 x 12 = 108 then divide it by 6 and yyou get 18 wich is 6 x 3

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2 years ago
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If p → q is true, then ~ p → ~ q is __________ true. always sometimes never
Yuliya22 [10]

Answer:

The correct answer is Never

6 0
1 year ago
A formula for 6 gallon of light green paint use 3/8 gallons of white paint. Liam has 9/16 gallon of white paint. Does liam have
FromTheMoon [43]

Answer:

Yes he have enough white paint.

Step-by-step explanation:

We are given

6 gallons of light green paint use → \frac{3}{8} gallons of white paint

using the unitary method

1 gallons of white paint → 6*8/3 gallons of light green paint

                                        → 16 gallons of light green paint

but Liam have 9/16 gallons of white paint

9/16 gallons of white paint → 16* 9/16 gallons of light green paint

                                             → 9 gallons of light green paint

Yes Liam have enough white paint to make 8 gallons of light green paint.  

3 0
2 years ago
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