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ehidna [41]
2 years ago
9

The seventh-grade class is building target areas for a PE activity. The bases for the game will be circular in shape. The diamet

er of each circle is 5 feet. Approximately how many square feet of the turf need to be painted for a base circle? Use 3.14 for π and round your answer to the nearest tenth
Mathematics
1 answer:
Scilla [17]2 years ago
8 0
To calculate the area it is pi*r^2

so since r = 1/2 d

2.5^2 * pi = area
or
19.625
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Factor this expression completely.<br> X^2-2x+24
pshichka [43]
There is no solutions, I think you got the signs mixed up.
7 0
3 years ago
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Solve for XX. Assume XX is a 2×22×2 matrix and II denotes the 2×22×2 identity matrix. Do not use decimal numbers in your answer.
sveticcg [70]

The question is incomplete. The complete question is as follows:

Solve for X. Assume X is a 2x2 matrix and I denotes the 2x2 identity matrix. Do not use decimal numbers in your answer. If there are fractions, leave them unevaluated.

\left[\begin{array}{cc}2&8\\-6&-9\end{array}\right]· X·\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right] =<em>I</em>.

First, we have to identify the matrix <em>I. </em>As it was said, the matrix is the identiy matrix, which means

<em>I</em> = \left[\begin{array}{ccc}1&0\\0&1\end{array}\right]

So, \left[\begin{array}{cc}2&8\\-6&-9\end{array}\right]· X·\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right] =  \left[\begin{array}{ccc}1&0\\0&1\end{array}\right]

Isolating the X, we have

X·\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right]= \left[\begin{array}{cc}2&8\\-6&-9\end{array}\right] -  \left[\begin{array}{ccc}1&0\\0&1\end{array}\right]

Resolving:

X·\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right]= \left[\begin{array}{ccc}2-1&8-0\\-6-0&-9-1\end{array}\right]

X·\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right]=\left[\begin{array}{ccc}1&8\\-6&-10\end{array}\right]

Now, we have a problem similar to A.X=B. To solve it and because we don't divide matrices, we do X=A⁻¹·B. In this case,

X=\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right]⁻¹·\left[\begin{array}{ccc}1&8\\-6&-10\end{array}\right]

Now, a matrix with index -1 is called Inverse Matrix and is calculated as: A . A⁻¹ = I.

So,

\left[\begin{array}{ccc}9&-3\\7&-6\end{array}\right]·\left[\begin{array}{ccc}a&b\\c&d\end{array}\right]=\left[\begin{array}{ccc}1&0\\0&1\end{array}\right]

9a - 3b = 1

7a - 6b = 0

9c - 3d = 0

7c - 6d = 1

Resolving these equations, we have a=\frac{2}{11}; b=\frac{7}{33}; c=\frac{-1}{11} and d=\frac{-3}{11}. Substituting:

X= \left[\begin{array}{ccc}\frac{2}{11} &\frac{-1}{11} \\\frac{7}{33}&\frac{-3}{11}  \end{array}\right]·\left[\begin{array}{ccc}1&8\\-6&-10\end{array}\right]

Multiplying the matrices, we have

X=\left[\begin{array}{ccc}\frac{8}{11} &\frac{26}{11} \\\frac{39}{11}&\frac{198}{11}  \end{array}\right]

6 0
3 years ago
A rectangular sheet of paper is 25/2cm long and 32/3 cm wide. Find its perimeter. *​
Zina [86]

Answer:

46.3cm

Step-by-step explanation:

  • perimeter is length around shape
  • 25/2 multiply by 2 becoz it's got two equal sides
  • 32/3 multiply by two for the other equal sides
  • add answers together to give you
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3 0
2 years ago
Read 2 more answers
What is the solutions for y=3x-5 and y=x-3
MArishka [77]

Answer: x=1, y=-2

Step-by-step explanation:

System

y=3x-5

y=x-3

3x-5=x-3

3x-x=-3+5

2x=2

x=2:2=1

y=x-3=1-3=-2

4 0
3 years ago
Which ordered pair is the solution to the system of equations?
tiny-mole [99]

Answer:

You can use Gaussian Elimination.

Double both sides of the first equation and add the second equation.

6x + 4y = 8

5x - 4y = 3

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11x      = 11

x = 1

5 - 4y = 3

-4y = -2

y = 1/2

Step-by-step explanation:

7 0
3 years ago
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