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adell [148]
3 years ago
9

If the discriminant of a quadratic equation is equal to -8, which statement describes the roots?

Mathematics
2 answers:
Dovator [93]3 years ago
5 0

Keywords

quadratic equation, discriminant, complex roots, real roots

we know that

The formula to calculate the <u>roots</u> of the <u>quadratic equation</u> of the form  ax^{2} +bx+c=0 is equal to

x=\frac{-b(+/-)\sqrt{b^{2}-4ac}}{2a}

where

The <u>discriminant</u> of the <u>quadratic equation</u>  is equal to

b^{2}-4ac

if  (b^{2}-4ac)> 0 ----> the <u>quadratic equation</u> has two <u>real roots</u>

if  (b^{2}-4ac)=0 ----> the <u>quadratic equation</u> has one <u>real root</u>

if  (b^{2}-4ac)< 0 ----> the <u>quadratic equation</u> has two <u>complex roots</u>

in this problem we have that

the <u>discriminant</u> is equal to -8

so

the <u>quadratic equation</u> has two <u>complex roots</u>

therefore

the answer is the option A

There are two complex roots

SVETLANKA909090 [29]3 years ago
3 0
Hello there, the correct answer is:

A.
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3 years ago
5. Based on recent results, scores on the SAT test are normally distributed with a mean of 1511 and a standard deviation of 312.
Mekhanik [1.2K]

Answer:

The actual SAT score is 2024.

The equivalent ACT score is 29.49.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

SAT score that is in the 95th percentile

Scores on the SAT test are normally distributed with a mean of 1511 and a standard deviation of 312, which means that \mu = 1511, \sigma = 312

95th percentile is X when Z has a pvalue of 0.95, so X when Z = 1.645. The score is:

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

1.645 = \frac{X - 1511}{312}

X - 1511 = 1.645*312

X = 2024

The actual SAT score is 2024.

Equivalent ACT score:

The equivalent ACT score is the 95th percentile of ACT scores.

Scores on the ACT test are normally distributed with a mean of 21.1 and a standard deviation of 5.1, which means that \mu = 21.1, \sigma = 5.1. So

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

1.645 = \frac{X - 21.1}{5.1}

X - 21.1 = 1.645*5.1

X = 29.49

The equivalent ACT score is 29.49.

5 0
2 years ago
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