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4 years ago

Evaluate the expression 2x^2 - x, when x = -3. Show all steps.

Mathematics

2 answers:

Alex_Xolod [135]4 years ago

5 0

Answer:

Step-by-step explanation:

2x² - x

2(-3)² - (-3)

2(9) + 3

18 + 3

V125BC [204]4 years ago

4 0

Answer:

Step-by-step explanation:

This is a substitution question,we are to substitute a given value in place of a certain letter

So let's solve

2x^2-x

And since x is given to be -3

So let's substitute

2(-3)^2-(-3)

2(9)-(-3)

18+3

So the final answer is 21

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3 years ago

Let X equal the number of typos on a printed page with a mean of 4 typos per page.

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a) There is a 98.17% probability that a randomly selected page has at least one typo on it.

b) There is a 9.16% probability that a randomly selected page has at most one typo on it.

Step-by-step explanation:

Since we only have the mean, we can solve this problem by a Poisson distribution.

In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:

$P(X = x) = \frac{e^{-\mu}*\mu^{x}}{(x)!}$

In which

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e = 2.71828 is the Euler number

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(a) What is the probability that a randomly selected page has at least one typo on it?

Thats is $P(X \geq 1)$ . Either a number is greater or equal than 1, or it is lesser. The sum of the probabilities must be decimal 1. So:

$P(X < 1) + P(X \geq 1) = 1$

$P(X \geq 1) = 1 - P(X < 1)$

In which

$P(X < 1) = P(X = 0)$ .

$P(X = 0) = \frac{e^{-4}*4^{0}}{(0)!} = 0.0183$

$P(X \geq 1) = 1 - P(X < 1) = 1 - 0.0183 = 0.9817$

There is a 98.17% probability that a randomly selected page has at least one typo on it.

(b) What is the probability that a randomly selected page has at most one typo on it?

This is $P = P(X = 0) + P(X = 1)$ . So:

$P(X = 0) = \frac{e^{-4}*4^{0}}{(0)!} = 0.0183$

$P(X = 1) = \frac{e^{-4}*4^{1}}{(1)!} = 0.0733$

$P = P(X = 0) + P(X = 1) = 0.0183 + 0.0733 = 0.0916$

There is a 9.16% probability that a randomly selected page has at most one typo on it.

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