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3 years ago

Will mark as brainliest if correct

Mathematics

1 answer:

Alenkinab [10]3 years ago

8 0

Answer:

x = 2

Step-by-step explanation:

9^2 or 9(9) = 81

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A circle has the order pairs (-1, 2) (0, 1) (-2, -1) what is the equation . Show your work.

olga55 [171]

We know that:

$(x-a)^2+(y-b)^2=r^2$

is an equation of a circle.

When we substitute x and y (from the pairs we have), we'll get a system of equations:

$\begin{cases}(-1-a)^2+(2-b)^2=r^2\\(0-a)^2+(1-b)^2=r^2\\(-2-a)^2+(-1-b)^2=r^2\end{cases}$

and all we have to do is solve it for a, b and r.

There will be:

$\begin{cases}(-1-a)^2+(2-b)^2=r^2\\(0-a)^2+(1-b)^2=r^2\\(-2-a)^2+(-1-b)^2=r^2\end{cases}\\\\\\
\begin{cases}1+2a+a^2+4-4b+b^2=r^2\\a^2+1-2b+b^2=r^2\\4+4a+a^2+1+2b+b^2=r^2\end{cases}\\\\\\
\begin{cases}a^2+b^2+2a-4b+5=r^2\\a^2+b^2-2b+1=r^2\\a^2+b^2+4a+2b+5=r^2\end{cases}\\\\\\
$

From equations (II) and (III) we have:

$\begin{cases}a^2+b^2-2b+1=r^2\\a^2+b^2+4a+2b+5=r^2\end{cases}\\--------------(-)\\\\a^2+b^2-2b+1-a^2-b^2-4a-2b-5=r^2-r^2\\\\-4a-4b-4=0\qquad|:(-4)\\\\\boxed{-a-b-1=0}$

and from (I) and (II):

$\begin{cases}a^2+b^2+2a-4b+5=r^2\\a^2+b^2-2b+1=r^2\end{cases}\\--------------(-)\\\\a^2+b^2+2a-4b+5-a^2-b^2+2b-1=r^2-r^2\\\\2a-2b+4=0\qquad|:2\\\\\boxed{a-b+2=0}$

Now we can easly calculate a and b:

$\begin{cases}-a-b-1=0\\a-b+2=0\end{cases}\\--------(+)\\\\-a-b-1+a-b+2=0+0\\\\-2b+1=0\\\\-2b=-1\qquad|:(-2)\\\\\boxed{b=\frac{1}{2}}\\\\\\\\a-b+2=0\\\\\\a-\dfrac{1}{2}+2=0\\\\\\a+\dfrac{3}{2}=0\\\\\\\boxed{a=-\frac{3}{2}}$

Finally we calculate $r^2$ :

$a^2+b^2-2b+1=r^2\\\\\\\left(-\dfrac{3}{2}\right)^2+\left(\dfrac{1}{2}\right)^2-2\cdot\dfrac{1}{2}+1=r^2\\\\\\\dfrac{9}{4}+\dfrac{1}{4}-1+1=r^2\\\\\\\dfrac{10}{4}=r^2\\\\\\\boxed{r^2=\frac{5}{2}}$

And the equation of the circle is:

$(x-a)^2+(y-b)^2=r^2\\\\\\\left(x-\left(-\dfrac{3}{2}\right)\right)^2+\left(y-\dfrac{1}{2}\right)^2=\dfrac{5}{2}\\\\\\\boxed{\left(x+\dfrac{3}{2}\right)^2+\left(y-\dfrac{1}{2}\right)^2=\dfrac{5}{2}}$

7 0

3 years ago

What is the slope of a line that is perpendicular to the line who’s equation is y=4/5x-3

alexandr402 [8]

This line y = 4/5 x - 3 has slope = 4/5

Perpendicular lines, slope is opposite and reciprocal so slope of a line that is perpendicular to the line y = 4/5 x - 3 is -5/4

Answer

- 5/4

8 0

3 years ago

Read 2 more answers

If g(x)=70−3x, find -g(-x)

Vedmedyk [2.9K]

Answer:

- g(- x) = - 70 - 3x

Step-by-step explanation:

to evaluate g(- x) substitute x = - x into g(x)

g(- x) = 70 - 3(- x) = 70 + 3x, hence

- g(- x) = - (70 + 3x) = - 70 - 3x

6 0

3 years ago

What are possible coordinates of point F if triangle DEF is<br> congruent to triangle ABC?

Lemur [1.5K]

Answer:

(-1, 4)

Step-by-step explanation:

Point B is 5 units below point A, and point E is 5 units above point D: AB = ED. This means that BC will be equal to EF. B and C are 7 units apart, so 7 units left from E is (-1, 4).

Hope this helps!

8 0

2 years ago

The claim is that the proportion of adults who smoked a cigarette in the past week is less than 0.30, and the sample statistics

IrinaK [193]

Answer: 0.84

Step-by-step explanation:

let p be the population proportion of adults who smoked a cigarette in the past week.

As per given , we have

$H_a: p$