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3 years ago

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There are 42 books in Mr. Long’s class library. Some books are paperback, some books are hard cover. There are 18 paperback book

s in her class library. What is the ratio of paperback books to hardcover books in Mr. Long’s library?
a)3:7. b)3:4. c)4:7. d)4:3

1 answer:

Vika [28.1K]3 years ago

7 0

Answer:

3:7

Step-by-step explanation:

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When 1 is subtracted from three- tenths of the number, the result is equal to one-fifth of a number. What is the number

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Based on the given mathematical statement, it can be rewritten into a mathematical equation to simplify and to be solved easily. The statement, "When one is subtracted from three-tenths of a number" corresponds to the equation, 3x/10 - 1, that is assuming the number is represented by the variable x. This is equal to one-fifth of the number. In other words,
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2 years ago

How to prove this???

swat32

$\cos^3 2A + 3 \cos 2A \\
\Rightarrow \cos 2A (\cos^2 2A + 3) \\
\Rightarrow (\cos^2 A - \sin^2 A) (\cos^2 2A + 3) \\
\Rightarrow (\cos^2 A - \sin^2 A) (1 - \sin^2 2A + 3) \\
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$

go to right side now

$4( \cos^6 A - \sin^6 A)\\
\Rightarrow 4( \cos^3 A - \sin^3 A)(\cos^3 A + \sin^3 A)$

use $x^3 - y^3 = (x-y)(x^2 + xy + y^2)$ and $x^3 + y^3 = x^2 - xy + y^2$

$4( \cos^6 A - \sin^6 A)\\ \Rightarrow 4( \cos^3 A - \sin^3 A)(\cos^3 A + \sin^3 A) \\
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~\quad \quad\cdot ( \cos A + \sin A)(\cos^2 A - \cos A \sin A + \cos^2 A)$

so $\sin^2 A + \cos^2 A = 1$

$4( \cos^6 A - \sin^6 A)\\ \Rightarrow 4(\cos A - \sin A)(\cos^2 A + \cos A \sin A + \sin^2 A) \\ ~\quad \quad\cdot ( \cos A + \sin A)(\cos^2 A - \cos A \sin A + \cos^2 A) \\ \Rightarrow 4(\cos^2 A - \sin^2 A)(1 + \cos A \sin A )(1- \cos A \sin A ) \\ \Rightarrow 4(\cos^2 A - \sin^2 A)(1 - \cos^2 A \sin^2 A )\\ \Rightarrow 4(\cos^2 A - \sin^2 A)(1 - \sin^2 A \cos^2 A ) \\
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2 years ago

Use Multistep Pythagorean Theorem to answer

uranmaximum [27]

Answer:

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Step-by-step explanation:

I think that is the answer I never come to such a question of changing things to radical form but I guess 5 cannot be multiplied by a number such that it has a square root so the answer is that√5

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2 years ago