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3 years ago

Solve by factorising x^2 + 8x + 15 = 0

Mathematics

1 answer:

Nutka1998 [239]3 years ago

3 0

Answer:

See below

Step-by-step explanation:

x² + 8x + 15 = 0

x² + 5x + 3x + 15 = 0

x x (x + 5) + 3x + 15 = 0

xx (x + 5) +3 (x + 5) = 0

(x + 5) × (x + 3) = 0 → x + 5 = 0 x + 3 = 0

x = -5

x + 3 = 0

x = -5

x = -3

x1 = -5

x2 = -3

Hope this helped ! :)

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Maksim231197 [3]

Answer:

A sample of 1077 is required.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

The margin of error is of:

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This means that $\pi = 0.42$

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So $\alpha = 0.02$ , z is the value of Z that has a pvalue of $1 - \frac{0.02}{2} = 0.99$ , so $Z = 2.327$ .

How large of a sample size is required?

A sample size of n is required, and n is found when M = 0.035. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.035 = 2.327\sqrt{\frac{0.42*0.58}{n}}$

$0.035\sqrt{n} = 2.327\sqrt{0.42*0.58}$

$\sqrt{n} = \frac{2.327\sqrt{0.42*0.58}}{0.035}$

$(\sqrt{n})^2 = (\frac{2.327\sqrt{0.42*0.58}}{0.035})^2$

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Rounding up:

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Step-by-step explanation:

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Step-by-step explanation:

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inna [77]

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