Help me please I’m not the smartest

X^2+4x+y^2-10y+20=30 find the center of the circle by completing the square

swat32

Answer:

a). Center of the circle = (-2, 5)

b). Equation of the line ⇒ y = $-\frac{4}{5}x+\frac{58}{5}$

Step-by-step explanation:

Equation of the circle is,

x² + 4x + y²- 10y + 20 = 30

a). [x² + 2(2)x + 4 - 4] + [y²- 2(5)y + 25] - 25 + 20 = 30

[x² + 2(2)x + 4] - 4 + [y² - 2(5)y + 25] - 25 + 20 = 30

(x + 2)² + (y - 5)²- 29 + 20 = 30

(x + 2)² + (y - 5)²- 9 = 30

(x + 2)² + (y - 5)² = 39

By comparing this equation with the standard equation of a circle,

Center of the circle is (-2, 5).

b). A point (2, 10) lies on this circle.

Slope of the line joining this point to the center (-2, 5),

$m_{1}=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

= $\frac{10-5}{2+2}$

= $\frac{5}{4}$

Let the slope of the tangent which is perpendicular to this line is ' $m_{2}$ '

Then by the property of perpendicular lines,

$m_{1}\times m_{2}=-1$

$\frac{5}{4}\times m_{2}=-1$

$m_{2}=-\frac{4}{5}$

Now the equation of the line passing though (2, 10) having slope $m_{2}=-\frac{4}{5}$

y - y' = $m_{2}(x-x')$

y - 10 = $-\frac{4}{5}(x-2)$

y - 10 = $-\frac{4}{5}x+\frac{8}{5}$

y = $-\frac{4}{5}x+\frac{8}{5}+10$

y = $-\frac{4}{5}x+\frac{58}{5}$

Therefore, equation of the line will be, y = $-\frac{4}{5}x+\frac{58}{5}$

7 0

3 years ago

Suppose that a jewelry store tracked the amount of emeralds they sold each week to more accurately estimate how many emeralds to

RUDIKE [14]

Answer:

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

And for this case the 95% confidence interval is given by (2.13; 2.37)

We have a point of estimate for the sample mean with this formula:

$\bar X = \frac{Upper+ Lower}{2}= \frac{3.37+2.13}{2}= 2.75$

And for the margin of error we have the following estimation:

$ME= \frac{Upper -Lower}{2}= \frac{3.37-2.13}{2}= 0.62$

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X$ represent the sample mean

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

And for this case the 95% confidence interval is given by (2.13; 2.37)

We have a point of estimate for the sample mean with this formula:

$\bar X = \frac{Upper+ Lower}{2}= \frac{3.37+2.13}{2}= 2.75$

And for the margin of error we have the following estimation:

$ME= \frac{Upper -Lower}{2}= \frac{3.37-2.13}{2}= 0.62$

5 0

3 years ago

Ben has a cell phone plan that provides 200 free minutes each month for a flat rate of $39. For any minutes over 200, Ben is cha

faltersainse [42]

Answer:

$\left\{\begin{matrix}39 & x\leq 200\\ 39+(x-200)\times 0.35 & x>200\end{matrix}\right.$

Step-by-step explanation:

We are given that Ben has a cell phone plan that provides 200 free minutes each month for a flat rate of $39.

We are also told that For any minutes over 200, Ben is charged $0.35 per minute.

let x be the minutes used each month

So, if $x\leq 200$

So, coat will be $39

If $x>200$

So, Ben is charged $0.35 per minute

So, when $x>200$

So, charge = $39+(x-200)\times 0.35$

So, the piecewise functions accurately represents charges based on Ben's cell phone :

$\left\{\begin{matrix}39 & x\leq 200\\ 39+(x-200)\times 0.35 & x>200\end{matrix}\right.$

4 0

3 years ago

Read 2 more answers

A university is trying to determine if certain remedial classes need to be offered to their incoming class. To do so, they give

lora16 [44]

Answer:

The experiment is identifying whether a student gets less than a 75% on the entrance exam.

The trial is one exam being taken.

An outcome is a student scoring 80%.

Step-by-step explanation:

An experiment occurs when an intervention is made by a researcher and its effect are studied, thus the experiment here is identifying whether a student gets less than a 75% on the entrance exam.

The trial is the one exam being taken.

While an outcome is the aftermath of the experiment which includes a student scoring 80%.

8 0

3 years ago

Factor out the GCF -2x^2 - 4x - 6

andrew-mc [135]

The Greatest Common factor(GCF) of -2x^2-4x-6 is -2(x+1)(x-3)

<h3>What is Greatest Common Factor?</h3>

The greatest common factor (GCF) is the largest factor two or more numbers have in common

From the question,

-2x^2-4x-6

By collecting like terms

-2(x^2-2x-3)

By factoring x^2-2x-3

-2(x^2-3x+1x-3)

Collecting like terms

-2(x^2-3x)+(x-3)

-2(x(x-3)+1(x-3))

-2(x+1)(x-3)

hence -2(x+1)(x-3) is the Greatest Common factor of -2x^2-4x-6 is

Learn more about Greatest Common factor on:brainly.com/question/219464

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3 0

10 months ago