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2 years ago

13

if alpha and beta are zeros of the polynomial x² - 6 X + k find k such that (alpha+beta)²-2alha beta =40

1 answer:

lidiya [134]2 years ago

8 0

Answer:

k = - 2

Step-by-step explanation:

Given α and β are the zeros of x² - 6x + k = 0 , with

a = 1, b = - 6 and c = k , then

α + β = - $\frac{b}{a}$ = - $\frac{-6}{1}$ = 6

αβ = $\frac{c}{a}$ = $\frac{k}{1}$ = k

Then solving

(α + β)² - 2αβ = 40

6² - 2k = 40

36 - 2k = 40 ( subtract 36 from both sides )

- 2k = 4 ( divide both sides by - 2 )

k = - 2

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X^2 - 4x - 77 = 0 Factor and check

Olenka [21]

X² - 4x - 77 = 0

( x + 7) ( x - 11)

x + 7 = 0

x - 11 = 0

x = -7
x = 11

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3 years ago

A quadrilateral has vertices at $(0,1)$, $(3,4)$, $(4,3)$ and $(3,0)$. Its perimeter can be expressed in the form $a\sqrt2+b\sqr

seraphim [82]

Answer:

a + b = 12

Step-by-step explanation:

Given

Quadrilateral;

Vertices of (0,1), (3,4) (4,3) and (3,0)

$Perimeter = a\sqrt{2} + b\sqrt{10}$

Required

$a + b$

Let the vertices be represented with A,B,C,D such as

A = (0,1); B = (3,4); C = (4,3) and D = (3,0)

To calculate the actual perimeter, we need to first calculate the distance between the points;

Such that:

AB represents distance between point A and B

BC represents distance between point B and C

CD represents distance between point C and D

DA represents distance between point D and A

Calculating AB

Here, we consider A = (0,1); B = (3,4);

Distance is calculated as;

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

$(x_1,y_1) = A(0,1)$

$(x_2,y_2) = B(3,4)$

Substitute these values in the formula above

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

$AB = \sqrt{(0 - 3)^2 + (1 - 4)^2}$

$AB = \sqrt{( - 3)^2 + (-3)^2}$

$AB = \sqrt{9+ 9}$

$AB = \sqrt{18}$

$AB = \sqrt{9*2}$

$AB = \sqrt{9}*\sqrt{2}$

$AB = 3\sqrt{2}$

Calculating BC

Here, we consider B = (3,4); C = (4,3)

Here,

$(x_1,y_1) = B (3,4)$

$(x_2,y_2) = C(4,3)$

Substitute these values in the formula above

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

$BC = \sqrt{(3 - 4)^2 + (4 - 3)^2}$

$BC = \sqrt{(-1)^2 + (1)^2}$

$BC = \sqrt{1 + 1}$

$BC = \sqrt{2}$

Calculating CD

Here, we consider C = (4,3); D = (3,0)

Here,

$(x_1,y_1) = C(4,3)$

$(x_2,y_2) = D (3,0)$

Substitute these values in the formula above

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

$CD = \sqrt{(4 - 3)^2 + (3 - 0)^2}$

$CD = \sqrt{(1)^2 + (3)^2}$

$CD = \sqrt{1 + 9}$

$CD = \sqrt{10}$

Lastly;

Calculating DA

Here, we consider C = (4,3); D = (3,0)

Here,

$(x_1,y_1) = D (3,0)$

$(x_2,y_2) = A (0,1)$

Substitute these values in the formula above

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

$DA = \sqrt{(3 - 0)^2 + (0 - 1)^2}$

$DA = \sqrt{(3)^2 + (- 1)^2}$

$DA = \sqrt{9 + 1}$

$DA = \sqrt{10}$

The addition of the values of distances AB, BC, CD and DA gives the perimeter of the quadrilateral

$Perimeter = 3\sqrt{2} + \sqrt{2} + \sqrt{10} + \sqrt{10}$

$Perimeter = 4\sqrt{2} + 2\sqrt{10}$

Recall that

$Perimeter = a\sqrt{2} + b\sqrt{10}$

This implies that

$a\sqrt{2} + b\sqrt{10} = 4\sqrt{2} + 2\sqrt{10}$

By comparison

$a\sqrt{2} = 4\sqrt{2}$

Divide both sides by $\sqrt{2}$

$a = 4$

By comparison

$b\sqrt{10} = 2\sqrt{10}$

Divide both sides by $\sqrt{10}$

$b = 2$

Hence,

a + b = 2 + 10

a + b = 12

3 0

3 years ago

A method for determining whether a critical point is a minimum. True or false?

natita [175]

Answer:

We can find if a critical point is a local minimum or maximum by looking at the second derivatives.

Step-by-step explanation:

If you take the first derivative, you will find the slope at the given point, which if it is a minimum or a maximum will be 0.

Then we take the second derivative. If that number is a positive number, then we have a local minimum. If it is a negative number, then it is a local maximum.

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3 years ago

If Sunil earns $3672 per month, what is his annual salary?

snow_tiger [21]

Answer:

$44064

Step-by-step explanation:

Sunil earns $3672 every month. To find out his annual salary, we will need to multiply this monthly salary by the number of months in a year; 12.

3672 * 12 = $44064

7 0

3 years ago

I don’t understand.<br> online school is hard

Minchanka [31]

I think you got to multiply the numbers hopefully I helped

5 0

3 years ago

Read 2 more answers