Help i dont know how to do this

Answer:

last option is correct

Step-by-step explanation:

(a-9)(a+9)

a(a+9)-9(a+9)

a^2+9a-9a-81  (plus 9a and minus -9a gets cancel)

a^2-81

a^2-9^2

Answer:

[tex]a^2-81[/tex]

Step-by-step explanation:

[tex](a-9)(a+9)[/tex]

Distribute, multiply everything in one of the parenthesis by everything in the other parenthesis,

[tex](a - 9)(a + 9)\\\\(a)(a)+(-9)(a)+(9)(a)+(-9)(9)[/tex]

Simplify, perform the multiplication and combine like terms,

[tex]a^2-9a+9a-81\\\\a^2-81[/tex]

Answer:

I think I explained the circle one before so I'll explain the left question because I wanted some points.

here,

area of circle is πr² which is given= 12 π cm²

so πr²= 12π

r= 2√3

d= 2r= 4√3

AB is diameter so AB= 4√3

Answer:

greater than 16 and less than 25(easy)

Using it's concept, it is found that the marginal relative frequency of survey participants who are girls is of 0.43.

A relative frequency is given by the number of desired outcomes divided by the number of total outcomes.

In this problem, we have that there were 2 + 3 + 5 + 4 + 3 + 8 + 2 + 6 + 4 + 3 = 40 participants, of which 17 are girls, hence the relative frequency is given by:

f = 17/40 = 0.425

Which is rounded to 0.43.

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Answer:

a

Step-by-step explanation:

Answer:

StartFraction one-fourth EndFraction left-parenthesis x right-parenthesis equals x left-parenthesis 30 plus 60 right-parenthesis.(x) = x(30 + 60)

Step-by-step explanation:

The equation that can be used is:

(1/4)*(30 min + 60 min + x) = x

So the correct option is the first one.

We know that Hiroshi spends:

The total time is:

30 min + 60 min + x

And we know that one-fourth of the total time that he studies is spent on math, then we can write:

(1/4)*(30 min + 60 min + x) = x

This is the equation we need to solve.

Solving it gives:

30 min + 60 min + x = 4x

90 min = 3x

(90 min)/3 = x = 30 min.

If you want to learn more about equations, you can read:

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22 chocolate cookies can be made from 5.50 cups of sugar and 7 lemon cookies can be made from 5.50 cups of sugar

An equation is an expression that shows the relationship between two or more numbers and variables.

The chocolate cookies is given as:

Number of chocolate cookies = 5.50 cups / 0.25 cup per cookie = 22

The lemon cookies is given as:

Number of lemon cookies = 5.50 cups / 0.75 cup per cookie = 7

22 chocolate cookies can be made from 5.50 cups of sugar and 7 lemon cookies can be made from 5.50 cups of sugar

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Answer:

y - 2 = -2(x +2)

Step-by-step explanation:

y - 2 = -2(x +2)

Answer:

100

Step-by-step explanation:

they are vertical angles therefore, they have the same measure.

Answer:

x = 4 and y = 5

Step-by-step explanation:

(x +1 , 4) = (5 , y -1)

compare the corresponding values

x + 1 = 5

x = 5 - 1

x = 4

4 = y - 1

4 + 1 = y

5 = y

The volume of the cone to the nearest whole number is 1283 m³

Formula for volume of a cone = [tex]\pi r^2\frac{h}{3}[/tex]

Slant height = 25m

If diameter = 14m , radius = 14/2 = 7m

Pie = 22/7

Substitute values into formula

We have,

Volume = [tex]3. 142 * 7 * 7 * \frac{25}{3}[/tex]

Volume = [tex]1,282. 98[/tex]

Volume = [tex]1283 m^3[/tex] in the nearest whole number

Thus, the volume of the cone to the nearest whole number is 1283 m³

Learn more about a cone here:

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Answer:

$2,000 at 9%

$8,000 at 4%

Step-by-step explanation:

(4x * .04) + (x * .09) = 500

.16x + .09x

.25x = 500

x = $2,000 at 9%

4x = $8,000 at 4%

Answer:

2000 at 9%

8000 at 4%

Step-by-step explanation:

Let the principle at 9% = x

The principle at 4% = 4*x

Together they give 500 dollars.

9% = .09

4% = ,04

Both are invested for 1 year

0.09 * 1 * x + 0.04 * 1 * 4x = 500

0.09x + 0.16x = 500

0.25x = 500

x = 500 / 0.25

x = 2000

She invested 2000 at 9%

She invested 4 * 2000 at 4%

Step-by-step explanation:

7x + 2 = 4x + 0

both sides substracted by 2

7x = 4x -2

both sides substracted by 4x

7x-4x = -2

3x = -2

both sides divided by 3

3x/3 = -2/3

=> x = -⅔

[tex]\\ \sf\bull\dashrightarrow 7x+2=4x+0[/tex]

[tex]\\ \sf\bull\dashrightarrow 7x+2=4x[/tex]

[tex]\\ \sf\bull\dashrightarrow 7x-4x=-2[/tex]

[tex]\\ \sf\bull\dashrightarrow 3x=-2[/tex]

[tex]\\ \sf\bull\dashrightarrow x=\dfrac{-2}{3}[/tex]

Answer:

The new price is 42.50

Step-by-step explanation:

First find the discount

50 *15%

50 *.15

7.5

Subtract this from the original price

50-7.5

42.50

The new price is 42.50

Answer:

Answer:

20

Step-by-step explanation:

"Product" indicates that we need to use multiplication.

The difference of 8 and 3 is 5 because 8-3=5

When we put it all together, it becomes

4(8-3)

4(5)

20

the product of 4 and the difference between 8 and 3

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The statement that is not true is

B. Perpendicular lines never intersect at right angles.

The definition of perpendicular lines is that they will intersect each other at 90 degree angles.

Answer:

B. Perpendicular lines never intersect at right angles.

Step-by-step explanation:

The perpendicular lines are lines that intersect at a right (90 degrees) angle. So, the option (B) is wrong and not true.

Answer:

c 52

Step-by-step explanation:

x=10

4 ×10=40

40+12=52

Answer:

25 1/4 inches

Step-by-step explanation:

Given :

Day ___ Mon ___ Tue ___ Wed ___ Thur ___Fri

△depth _-3/8 ___ - 1/8 ___ 1/2 ____ - 1/4 __ 3/4

Depth of water at the beginning = 24 3/4

Depth of water at the end of Friday:

24 3/4 - 3/8 - 1/8 + 1/2 - 1/4 + 3/4

24 3/4 + (-3/8 - 1/8 + 1/2 - 1/4 + 3/4)

24 3/4 + (-1/2 + 1/2 + 3/4)

24 3/4 + ( - 1/4 + 3/4)

24 3/4 + 1/2

24 + (1 1/4

24+ 1 + 1/4

25 1/4

Answer:

if two lines in a linear system INTERSECT, they have exactly one point in common.

Answer:

cross each other

Step-by-step explanation:

The point of intersection is the point where both lines will have the same coordinates.

Answer:

Step-by-step explanation:

There are 6 qualifying letters, out of 26.

Thus, the probability that Luca will win through one wheel spin is

6/26, or 3/13, or 0.23.

This is a theoretical probability, since it could be calculated with the same result over and over.  An experimental probability, on the other hand, would be the result if the probability stemmed from experimenting:  making a list of all 26 letters and then spinning the wheel over and over again, perhaps 100 times, and recording how many times each of the 26 letters shows up.

Answer:

Rain is correct, calculates correctly, 238.5 square inches

Step-by-step explanation:

The given triangular pyramid is shown with the dimensions.

The surface area of the triangular pyramid is given by :

[tex]$A=\frac{1}{2}\left(a \times b\right) + 3\left(\frac{1}{2}\times b\times s\right)$[/tex]

[tex]$A=\frac{1}{2}\left(10 \times 8.7\right) + 3\left(\frac{1}{2}\times 10\times 13\right)$[/tex]

[tex]$A=43.5+(3\times 65)$[/tex]

[tex]$A=43.5+195$[/tex]

[tex]$A=238.5 \ \text{inche}^2$[/tex]

Therefore, the surface area of the triangular pyramid is = 238.5 square inches.

Answer:

16. 1

17. 3

18. 1

19. 1

20. 1

Step-by-step explanation:

I'm sorry that I don't speak in Filipino but I can help fill in the blanks.

(In brackets is the English translation)

12 pulgada = 1 piye (12 inch is 1 foot)

1 yard = 3 piye (1 yard is 3 feet)

10 sentimetro = 1 desimetro (10 centimeters is 1 decimeter)

1000 metro = 1 kilometro (1000 meters is 1 kilometer)

10 millimetro = 1 sentimetro (10 millimeters is 1 centimeter)

Answer:

mean: 4.5 (1dp)

median: 4

mode: 6

Step-by-step explanation:

mean:

0 + 1 + 1 + 2 + 2 + 2 + 2 + 3 + 3 + 3 + 4 + 4 + 4 + 5 + 5 + 6 + 6 + 6 + 6 + 6 + 7 + 8 + 8 + 9 + 10 = 113

113 divided by 25 = 4.52, or just 4.5 (rounded to one decimal place

median:

(middle) = 4

mode:

(most occurring) = 6

Answer:

4/11

Step-by-step explanation:

Let :

x = numerator

x + 7 = denominator [tex]\frac{x}{x + 7}[/tex]

[tex]\frac{x}{x+7} + \frac{1}{4} = \frac{1}{3}[/tex]

[tex]\frac{x + 1}{x + 11} = \frac{1}{3}[/tex]

cross multiply

3(x + 1) = x + 11

3x + 3 = x + 11

combine like terms

3x - x = 11 - 3

2x = 8

x = 4

x + 7 = 4 + 7 = 11

original fraction = 4/11

Answer: 31.2

Step-by-step explanation: