8th Grade Math Pls help, I'll mark Brainiest for the First Correct answer

Which polynomial identity will prove that 19 = 27 − 8?

3241004551 [841]

The answer is Difference of Cubes.

Difference of cubes is a³ - b³.
27 can be written as 3³ (= 3 × 3 × 3 = 27). So, a = 3.
8 can be written as 2³ (= 2 × 2 × 2 = 8). So, b = 2.

Difference of cubes can be expressed as:
a³ - b³ = (a - b)(a² + ab + b²)
⇒ 3³ - 2³ = (3 - 2)(3² + 3×2 + 2²) = 1 × (9 + 6 + 4) = 1 × 19 = 19
⇒ 27 - 8 = 19

5 0

3 years ago

Is the ordered pair (-2, 1) a solution to the equation - 3x + y = 5? <br>No <br>Yes

Otrada [13]

Answer:

No

Step-by-step explanation:

Plug (-2,1) into -3x+y=5. This will make it -3(-2)+(1)=5. This is equal to 6+1=5. 7=5. 7 is not equal to 5. Therefore, (-2,1) is not a solution to the equation -3x+y=5.

If this helps please mark as brainliest

6 0

3 years ago

What is the mean (average) for -36, -25, 12, -4, 18?

Alina [70]

To find the mean add all the numbers up then divide by how many numbers you have.

-36+(-25)+12+(-4)+18= (-35)

there are a total of five numbers so divide by 5

(-35)/5=(-7)

answer -7

3 0

3 years ago

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What set of transformations could be applied to rectangle ABCD to create A″B″C″D″? 'Rectangle formed by ordered pairs A at negat

CaHeK987 [17]

Answer:

Reflection over the y-axis and rotation of 180°

Step-by-step explanation:

We have,

Rectangle ABCD with co-ordinates A(-4,2), B(-4,1), C(-1,1) and D(-1,2).

It is transformed to a new rectangle A'B'C'D' with co-ordinates A'(-4,-2), B'(-4,-1), C'(-1,-1) and D'(-1,-2).

The graph of both the triangles is shown below.

we see that,

The rectangle ABCD is reflected about y-axis and then rotated 180° to obtain A'B'C'D'.

Reflected about y-axis Rotation of 180°

A= (-4,2) (4,2) A'= (-4,-2)

B= (-4,1) (4,1) B'= (-4,-1)

C= (-1,1) (1,1) C'= (-1,-1)

D= (-1,2) (1,2) D'= (-1,-2)

Hence, the second rectangle is formed by: Reflection over the y-axis and rotation of 180°.

5 0

3 years ago

Read 2 more answers

A researcher claims that the variation in the salaries of elementary school teachers is greater than the variation in the salari

guajiro [1.7K]

Answer:

a

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

b

$F_{critical} = 1.8608$

c

$F = 2.9085$

d

The decision rule is

Reject the null hypothesis

e

There is sufficient evidence to support the researchers claim

Step-by-step explanation:

From the question we are told that

The first sample size is $n_1 = 30$

The sample variance for elementary school is $s^2_1 = 8324$

The second sample size is $n_2 = 30$

The sample variance for the secondary school is $s^2_2 = 2862$

The significance level is $\alpha = 0.05$

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

Generally from the F statistics table the critical value of $\alpha = 0.05$ at first and second degree of freedom $df_1 = n_1 - 1 = 30 - 1 = 29$ and $df_2 = n_2 - 1 = 30 - 1 = 29$ is