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3 years ago

NEED HELPPPPPPP!!!!!!! PLEASE!!!!!!!!

Mathematics

1 answer:

vagabundo [1.1K]3 years ago

4 0

Firstly, simplife the function $-x^3-x^2+4x+4$ in the following way:

$-x^3-x^2+4x+4=-(x^3+x^2)+4(x+1)=-x^2(x+1)+4(x+1)=(x+1)(4-x^2)=(x+1)(2-x)(2+x)=-(x+2)(x+1)(x-2)$ .

There are three x-intercepts: x=-1; x=2 and x=-2 (therefore, options A and D are incorrect).

Since before brackets is sign "-", you should state that graph starts down on the left (you can check this substituting smaller negative number than -2 into function expression. For example, if x=-10, then f(-10)=-(-10+2)(-10+1)(-10-2)=-(-8)(-9)(-12)>0) and goes up on the right (you can check this substituting greater positive number than 2 into function expression. For example, if x=10, then f(-10)=-(10+2)(10+1)(10-2)=-(12)(11)(8)<0).

Answer: correct choice is B.

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If random samples of size 11 are drawn from a population with mean 7 and standard deviation 3 , find the standard error of the d

allsm [11]

Here,

n = 11

mean = 7

Standard Deviation (σ) = 3

S.E. = ?

We know that,

S.E. = σ/ $\sqrt{n}$

S.E. = 3/ $\sqrt{11}$

∴ S.E. = 0.905 Ans.

5 0

3 years ago

2)<br> 8xy -- 3y + 2 ( 9x - 5y + 4 ) if x = 3, y = - 4

Scilla [17]

Answer:

8xy-3y + 2(9x-5y+4) = 18

Step-by-step explanation:

We need to find the value of the given expression:

8xy-3y + 2(9x-5y+4) ....(1)

when x = 3 and y = -4

Put the values of a and y in equation (1)

8×3×(-4)-3(-4)+ 2(9×3-5(-4)+4)

= -96 +12 + 2(27 + 20 +4)

= -84 + 2(51)

= -84 + 102

= 18

Hence, the value of the given expression is 18.

4 0

3 years ago

Which expression is equivalent to (2r2+r - 1) – (3r2+48 - 5)?

BigorU [14]

Answer:

$-r^2-3r+4$

Step-by-step explanation:

The question is to simplify the expression $(2r^2+r-1)-(3r^2+4r-5)$

First, we can eliminate the 2nd parenthesis expression by changing signs of all the terms since there is a "-" sign in front. Then we add the "Like Terms". The process is shown below:

$(2r^2+r-1)-(3r^2+4r-5)\\=2r^2+r-1-3r^2-4r+5\\=-r^2-3r+4$

The first answer choices (has some typos) is correct. The correct answer is $-r^2-3r+4$

7 0

3 years ago

A film distribution manager calculates that 7% of the films released are flops. If the manager is correct, what is the probabili

diamong [38]

Answer:

0.9909 = 99.09% probability that the proportion of flops in a sample of 404 released films would be greater than 4%

Step-by-step explanation:

I am going to use the binomial approximation to the normal to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

In this problem, we have that:

$p = 0.07, n = 404$ . So

$\mu = E(X) = np = 404*0.07 = 28.28$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{404*0.07*0.93} = 5.13$

If the manager is correct, what is the probability that the proportion of flops in a sample of 404 released films would be greater than 4%?

This is the pvlaue of Z when X = 0.04*404 = 16.16. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{16.16 - 28.28}{5.13}$

$Z = -2.36$

$Z = -2.36$ has a pvalue of 0.0091

1 - 0.0091 = 0.9909

0.9909 = 99.09% probability that the proportion of flops in a sample of 404 released films would be greater than 4%

7 0

4 years ago

Hill in the blank: Type your answer in the box and then clichWhat is the value of n?144eAnswer:

Inessa05 [86]

The correct answer is $95$ °.

To solve for $n$ , you can start by finding the measures of the triangle's interior angles. Knowing that a straight line measures $180$ °, you can subtract the given values from $180$ ° to find the measures of the respective supplementary interior angles. That would give you $59$ ° $(180-121)$ and $36$ ° $(180-144)$ .

Now, knowing that the measure of all the interior angles of a triangle is also $180$ °, you can add the two interior angles you know $(59+36)$ and subtract those from $180$ °. Doing so would give you the measure of the missing third angle, which is $85$ °.

Finally, because angle $n$ is the supplementary angle of the missing angle from the previous step, simply subtract that angle's measure from $180$ ° to find $n$ °, which is $180-85$ or $95$ °.

5 0

4 years ago