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Vinvika [58]
4 years ago
9

What is the radius of a circle represented by the equation x²+y²x²+y²-2x+4y-18=0

Mathematics
1 answer:
REY [17]4 years ago
5 0

Answer:

Step-by-step explanation:

i think eq. of circle is

x²+y²-2x+4y-18=0

compare with x²+y²+2gx+2fy+c=0

center is (-g,-f) or (1,-2)

radius is √(g²+f²-c)=√((1)²+(-2)²-(-18))

=√(1+4+18)

=√23

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-12=-8z+12 (solve for z) grade lvl. 7
jeka57 [31]

Answer:

3 =z

Step-by-step explanation:

-12=-8z+12

Subtract 12 from each side

-12-12 = -8z+12-12

-24 = -8z

Divide by -8

-24/-8 = -8z/-8

3 =z

8 0
4 years ago
A culture of bacteria has an initial population of 650 bacteria and doubles every 9 hours. Using the formula Pt=P0⋅2tdP_t = P_0\
Ghella [55]
So is doubling, first off, meaning, if the current amount say P, then when it doubles is 2P, or double that, or P + P, so the rate of growth is 100%, since it's doubling.

and is doing it every 9 hour cycle, thus

\bf \textit{Periodic/Cyclical Exponential Growth}\\\\
A=P(1 + r)^{\frac{t}{c}}\qquad 
\begin{cases}
A=\textit{accumulated amount}\\
P=\textit{initial amount}\to &650\\
r=rate\to 100\%\to \frac{100}{100}\to &1.00\\
t=\textit{elapsed time}\to &10\\
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\end{cases}
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A=650(1 + 1)^{\frac{10}{9}}\implies A=650(2)^{\frac{10}{9}}\implies A=650\sqrt[9]{2^{10}}
4 0
3 years ago
A company needs to package 2,400 pencils. A box in the shape of a rectangular prism can hold 60 pencils. A cylindrical container
Sergio039 [100]

Answer:

The rectangular prism boxes should be used because they will cost the company $2.50 less than using the cylindrical containers.

Step-by-step explanation:

Box

2400/60 * .5 = 20

Cylinder

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Box cost 2.50 less

7 0
3 years ago
Read 2 more answers
Find an exact value.
Westkost [7]

Answer:

\displaystyle \cos\left(-\frac{7\,\pi}{12}\right) = \frac{\sqrt{2} - \sqrt{6}}{4}.

Step-by-step explanation:

Convert the angle \displaystyle \left(-\frac{7\, \pi}{12}\right) to degrees:

\displaystyle \left(-\frac{7\, \pi}{12}\right) = \left(-\frac{7\, \pi}{12}\right) \times \frac{180^\circ}{\pi} = -105^\circ.

Note, that \left(-105^\circ\right) is the sum of two common angles: \left(-45^\circ\right) and \left(-60^\circ\right).

  • \displaystyle \cos\left(-45^\circ\right) = \cos\left(45^\circ\right) = \frac{\sqrt{2}}{2}.
  • \displaystyle \cos\left(-60^\circ\right) = \cos\left(60^\circ\right) = \frac{1}{2}.
  • \displaystyle \sin\left(-45^\circ\right) = -\sin\left(45^\circ\right) = -\frac{\sqrt{2}}{2}.
  • \displaystyle \sin\left(-60^\circ\right) = -\sin\left(60^\circ\right) = -\frac{\sqrt{3}}{2}.

By the sum-angle identity of cosine:

\cos(A + B) = \cos(A)\cdot \cos(B) - \sin(A) \cdot \sin(B).

Apply the sum formula for cosine to find the exact value of \cos\left(-105^\circ \right).

\begin{aligned}\cos\left(-105^\circ \right) &= \cos\left(\left(-45^\circ\right) + \left(-60^\circ\right)\right) \\ &= \cos\left(-45^\circ\right) \cdot \cos\left(-60^\circ\right)\right) - \sin\left(-45^\circ\right) \cdot \sin\left(-60^\circ\right)\right) \\ &= \frac{\sqrt{2}}{2} \times \frac{1}{2} - \left(-\frac{\sqrt{2}}{2}\right)\times \left(-\frac{\sqrt{3}}{2}\right) = \frac{\sqrt{2} - \sqrt{6}}{4}\end{aligned}.

\displaystyle \left(-\frac{7\, \pi}{12}\right) = \left(-\frac{7\, \pi}{12}\right) \times \frac{180^\circ}{\pi} = -105^\circ. In other words, \displaystyle \left(-\frac{7\, \pi}{12}\right) and \left(-105^\circ\right) correspond to the same angle. Therefore, the cosine of \displaystyle \left(-\frac{7\, \pi}{12}\right)\! would be equal to the cosine of \left(-105^\circ\right)\!.

\displaystyle \cos\left(-\frac{7\,\pi}{12}\right) = \cos\left(-105^\circ\right) = \frac{\sqrt{2} - \sqrt{6}}{4}.

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Answer:

4 with a rational sign

Step-by-step explanation:

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