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2 years ago

Solve x2 – 18x + 81 = 4 by completing the square. Select any solutions that apply.

Mathematics

1 answer:

Masteriza [31]2 years ago

3 0

Answer:

7 and 11

Step-by-step explanation:

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Which are the solutions of x2 = –7x – 8?

vovangra [49]

Answer:

The solutions are:

$x_1=\frac{-7+\sqrt{17}}{2}$ $x_2=\frac{-7-\sqrt{17}}{2}$

Step-by-step explanation:

We have the following quadratic equation

$x^2 = -7x - 8$

We can rewrite the equation as follows

$x^2+7x + 8=0$

Now we use the quadratic formula to solve the equation

For an equation of the form $ax ^ 2 + bx + c = 0$ the quadratic formula is:

$x=\frac{-b\±\sqrt{b^2-4ac}}{2a}$

In this case:

$a=1,\ b=7,\ c=8$

Then:

$x=\frac{-7\±\sqrt{7^2-4(1)(8)}}{2(1)}$

$x=\frac{-7\±\sqrt{49-32}}{2}$

$x=\frac{-7\±\sqrt{17}}{2}$

$x_1=\frac{-7+\sqrt{17}}{2}$

$x_2=\frac{-7-\sqrt{17}}{2}$

7 0

3 years ago

Read 2 more answers

I need all the answers

vodomira [7]

I don’t see the questions?!

8 0

2 years ago

Read 2 more answers

Work out the area of a rectangle with base, b=28mm and perimeter, P=74mm.

zhannawk [14.2K]

Answer:

$28 \times 2 =5 6 \\ 74 - 56 = 18 \\ 18 \div 2 = 9 \\ width = 9 \\ area = 9 \times 28 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 252mm ^{2}$

3 0

2 years ago

Read 2 more answers

The area of a triangle is 1,4440 cm^2. The base of the triangle is 5 times the height. What is the height of the triangle?

DochEvi [55]

Answer:

h = 24 cm

Step-by-step explanation:

The formula for area of a triangle is

A = (1/2)bh where b is the base and h is the height.

We are told that the base is 5 times the height, this translates to

b = 5h, so we can rewrite our formula to

A = (1/2)(5h)(h) or

A = (1/2)5h²

We are given A = 1,440, so plug that in and solve for h...

1,440 = (1/2)5h²

2,880 = 5h² (multiply both sides by 2 to get rid of the fraction)

576 = h² (divide both sides by 5 to get the h value by itself)

24 = h (take the square root of both sides)

3 0

2 years ago

A cylinder and cone have the same height and radius. The height of each is 5 cm, and the radius is 2 cm. Calculate the volume of

never [62]

Answer:

The volume of a cylinder is 62.8 cm and the volume of a cone is 20.9 cm³ .

Step-by-step explanation:

Formula

$Volume\ of\ a\ cylinder = \pi r^{2} h$

$Volume\ of\ a\ cone = \pi r^{2} \frac{h}{3}$

Where r is the radius and h is the height .

As given

A cylinder and cone have the same height and radius. The height of each is 5 cm, and the radius is 2 cm.

$\pi = 3.14$

Thus

$Volume\ of\ a\ cylinder =3.14\times 5\times 2\times 2$

= 62.8 cm³

Thus the volume of a cylinder is 62.8 cm³ .

$Volume\ of\ a\ cone = 3.14\times 2\times 2\times frac{5}{3}$

$Volume\ of\ a\ cone =\frac{5\times 3.14\times 2\times 2}{3}$

$Volume\ of\ a\ cone =\frac{62.8}{3}$

= 20.9 (Approx) cm³

Thus the volume of a cone is 20.9 cm³ .

Therefore the volume of a cylinder is 62.8 cm and the volume of a cone is 20.9 cm³ .

8 0

3 years ago