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3 years ago

Is -√15 an imaginary or irrational number?

Mathematics

2 answers:

Leno4ka [110]3 years ago

7 0

Hey there! I'm happy to help!

An irrational number is a real number that can't be written as a ratio of two other integers (non-fraction numbers) so a number like π or √2.

An imaginary number is one that breaks a mathematical rule so it can't necessarily exist as a real number. The main imaginary number is i, and here is the thing it does that breaks the rules and makes it imaginary:

i²=-1

√-1=i

We know that you cannot square a real number and have it be negative because a negative number can only be obtained by multiplying a positive and a negative number. This also shows us that there cannot be a square root of a negative number.

We have the number -√15. The placement of that negative sign is CRUCIAL! The square root of any positive integer is going to be a real number, but the square root of a negative number is nonexistent aka imaginary. √-15 would be an imaginary number, but we have -√15, which is the same thing as -1·√15. The negative sign is not inside the square root, which makes it not imaginary, so this is an irrational number. You can plug it into a calculator and it would be -3.872983346....

Have a wonderful day and keep on learning :)

Kazeer [188]3 years ago

6 0

Answer:

irrational

$\sqrt{-15}$ would be imaginary

Step-by-step explanation:

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caleb has 7 black caps 4 yellow caps and 9 blue caps in his wardrobe. Two caps are drawn wothout replacement from the wardrobe.

Hitman42 [59]

Answer:

18/95

Step-by-step explanation:

What is probability?

Probability is simply the chances of something occuring.

As a formula, I like to say that formula = # of favorable outcomes / total # of outcomes

Where favorable outcomes is what we want to happen and total # of outcomes is the total number of possibilities.

In order to find the probability of the occurrence of something in a row, we multiply the individual probabilities of each action

Understanding the question

Here we are given that caleb has 7 black caps 4 yellow caps and 9 blue caps in his wardrobe and given this we want to find the probability of Caleb randomly selecting 2 blue caps without replacing it the first being drawn.

So here # of favorable outcomes = # of blue caps = 9

and

total number of outcomes = total # of caps = 7 + 4 + 9 = 20

Finding the probability

For first draw

First let's find the probability that caleb will select a blue cap the first time.

We know that probability = # of favorable outcomes / total # of outcomes

We also know that # of favorable outcomes = 9 and total # of outcomes = 20

Plugging this in, we get that the probability of Caleb randomly selecting a blue cap on the first draw is 9/20

For second draw

Because it says that caleb will not replace the cap when drawn it's important to subtract 1 from both the # of caps and # of blue caps

This results us in having # of favorable outcomes as 8 and total # of outcomes as 19

Plugging this in we get that the probability of Caleb drawing a blue cap the second time is 8/19

Finally to find the total probability of him selecting two blue caps in a row without replacing the first cap, we multiply the individual probabilities

From doing so we acquire 9/20 * 8/19 = 18/95

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2 years ago

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kati45 [8]

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3 years ago

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A monkey is swinging from a tree. On each swing, she travels along an arc that is 75% as long as the previous swing's arc. The t

mr_godi [17]

Answer:

Total length of the first swing=64 m

Step-by-step explanation:

The total length of all four swings can be expressed as;

Total length of all 4 swings=Length of first swing+length of second swing+length of third swing+length of fourth swing

where;

Total length of all 4 swings=175 m

Length of first swing=x

Length of second swing=75% of length of first swing=(75/100)×x=0.75 x

Length of third swing=75% of length of second swing

Length of third swing=(75/100)×0.75 x=0.5625 x

Length of fourth swing=75% of length of third swing

Length of fourth swing=(75/100)×0.5625 x=0.421875 x

replacing;

Total length of all 4 swings

175=x+0.75 x+0.5625 x+0.421875 x

2.734375 x=175

x=175/2.734375

x=64

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Answer:

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Step-by-step explanation:

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