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3 years ago

Solve x2 + 9x + 9 = 0.

2 answers:

8 0

X = (-b (+-)sqrt (b^2 - 4ac) / 2a

x^2 + 9x + 9 = 0
a = 1
b = 9
c = 9

x = -9 (+-) sqrt (9^2 - 4(1)(9)) / 2(1)
x = -9 (+-) sqrt (81 - 36) / 2
x = -9 (+-) sqrt (45) / 2
x = -9 (+-) sqrt (9 * 5) / 2
x = -9 (+-) (3 sqrt 5) / 2 <===

LekaFEV [45]3 years ago

4 0

$x^2 + 9x + 9 = 0\\ \\ D=b^2-4ac=9^2-4*1*9=81-36= 45 \\ \\ x_{1,2}= \frac{-bб \sqrt{D} }{2a} \\ \\ x_{1,2}= \frac{-9б \sqrt{45} }{2}= \frac{-9б3 \sqrt{5} }{2}$

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PLEASE HELP

Ksivusya [100]

Answer:

Option (1)

Step-by-step explanation:

Coordinates of the vertices of a quadrilateral WXYZ drawn in the figure are,

W(-1, 4), X(2, 2), Y(0, -1), Z(-3, 1)

Length of a segment having ends as $(x_1, y_1)$ and $(x_2, y_2)$ is represented by,

d = $\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$

Length of WX = $\sqrt{(-1-2)^2+(4-2)^2}$

= $\sqrt{9+4}$

= $\sqrt{13}$

Length of XY = $\sqrt{(2-0)^2+(2+1)^2}$

= $\sqrt{13}$

Length of YZ = $\sqrt{(0+3)^2+(-1-1)^2}$

= $\sqrt{13}$

Length of ZW = $\sqrt{(-1+3)^2+(4-1)^2}$

= $\sqrt{13}$

Slope of side WX ( $m_1$ ) = $\frac{y_2-y_1}{x_2-x_1}$

= $\frac{4-2}{-1-2}$

= $-\frac{2}{3}$

Slope of side XY ( $m_2$ ) = $\frac{2+1}{2-0}$

= $\frac{3}{2}$

By the property of perpendicular lines,

$m_1\times m_2=-1$

$(-\frac{2}{3})(\frac{3}{2})=-1$

therefore, WX and XY are perpendicular.

Slope of YZ ( $m_3$ ) = $\frac{-1-1}{0+3}=-\frac{2}{3}$

$m_2\times m_3=(\frac{3}{2})\times (-\frac{2}{3})=-1$

Therefore, XY ⊥ YZ

Similarly, we can prove YZ ⊥ ZW.

Therefore, quadrilateral WXYZ is a SQUARE.

Option (1) will be the answer.

7 0

3 years ago

Solve Ax − By = C for x.

Travka [436]

For this case we have the following equation:

$Ax - By = C$

From here, we must clear the value of x.

Adding By on both sides:

$Ax = By + C$

Then, dividing both sides by A we have:

$x = \frac {By + C} {A}$

Answer:

$x = \frac {By + C} {A}$

x equals the quantity B times and plus C all over A

5 0

3 years ago

Find the value of k

andrey2020 [161]

The slope of the line given is 1 because that is the coefficient in front of x. A slope is found by dividing the change in y by the change in x. Knowing this, we can set up an equation with the points given.

1 = (-2 - k)/(-7 +1)

Now we'll solve to find k.
Firstly we'll multiple both sides by (-7 + 1):

1(-7 + 1) = (-2 - k)/(-7 +1)(-7 + 1)
-7 = -2 - k

Now we'll add 2 to both sides:
-7 + 2 = -2 - k + 2
-5 = -k

Now to get k by itself we must divide by negative one on both sides:
-5/(-1) = -k/(-1)
5 = k

Your answer is 5 = k

7 0

3 years ago

A study indicates that 18- to 24- year olds spend a mean of 140 minutes watching video on their smartphones per month. Assume

malfutka [58]

Answers:

a) 0.091

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 140 minutes

Standard Deviation, σ = 15 minutes

We are given that the distribution of time watching videos is a bell shaped distribution that is a normal distribution.

Formula: