Algebra II : Algebra II

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #2831 : Algebra Ii

Simplify the expression \displaystyle \frac{8!}{5!}

Possible Answers:

\displaystyle 5!

\displaystyle 56

\displaystyle 120

\displaystyle 336

\displaystyle 8!

Correct answer:

\displaystyle 336

Explanation:

\displaystyle \frac{8!}{5!}=\frac{8*7*6*5*4*3*2*1}{5*4*3*2*1}

The 5,4,3,2,1 cancel out leaving 8*7*6 which is 336

Example Question #23 : Factorials

Multiply the factorials:  \displaystyle 4!\times 3!

Possible Answers:

\displaystyle \textup{The answer is not given.}

\displaystyle 144

\displaystyle 12

\displaystyle 4.79\times 10^{8}

\displaystyle 169

Correct answer:

\displaystyle 144

Explanation:

Rewrite the factorials.

\displaystyle 4! = 4\times3\times2\times1 = 24

\displaystyle 3!=3\times2\times1 = 6

Multiply these two numbers together.

\displaystyle 24\times 6 = 144

The answer is:  \displaystyle 144

Example Question #24 : Factorials

Divide the factorials:  \displaystyle \frac{6!}{3!}

Possible Answers:

\displaystyle 120

\displaystyle 720

\displaystyle 40

\displaystyle 360

\displaystyle 240

Correct answer:

\displaystyle 120

Explanation:

Expand both factorials in the numerator and denominator.

\displaystyle \frac{6!}{3!} = \frac{6 \times 5\times4\times3\times2\times1}{3\times2\times1}

Cancel the common terms on the numerator and denominator.

The numerator becomes:  

\displaystyle 6\times 5 \times 4 =120

The answer is:  \displaystyle 120

Example Question #22 : Multiplying And Dividing Factorials

Simplify the factorials:  \displaystyle \frac{3!(3!+2!)^2}{5! }

Possible Answers:

\displaystyle \frac{16}{5}

\displaystyle 15

\displaystyle \frac{32}{5}

\displaystyle 720

\displaystyle \frac{120}{7}

Correct answer:

\displaystyle \frac{16}{5}

Explanation:

Do not add the factorials!

\displaystyle 3!+2! \neq 5!

We will need to simplify and rewrite the terms of the factorials.

\displaystyle \frac{3!(3!+2!)^2}{5!} = \frac{(3\times 2\times 1)[(3\times 2\times 1)+(2\times 1)]^2}{5\times 4\times3\times 2\times 1}

The common terms in the numerator and denominator can be simplified.

\displaystyle \frac{[(3\times 2\times 1)+(2\times 1)]^2}{5\times 4}

Simplify the numerator and denominator.

\displaystyle \frac{[6+2]^2}{20} = \frac{8^2}{20} = \frac{64}{20} =\frac{4\times 4\times 4}{5\times 4}

Simplify the fraction by cancelling the common terms.

The answer is:  \displaystyle \frac{16}{5}

Example Question #26 : Factorials

Solve:  \displaystyle 3!(\frac{(4+3)!}{7(5!)})

Possible Answers:

\displaystyle \frac{1}{20}

\displaystyle \frac{1}{14}

\displaystyle 18

\displaystyle \frac{1}{40}

\displaystyle 36

Correct answer:

\displaystyle 36

Explanation:

Rewrite all the factorial terms in expanded form.  To expand a factorial, multiply all the integers in decreasing order until it reaches to one.

\displaystyle 3!(\frac{(4+3)!}{7(5!)}) = (3\times 2\times 1)(\frac{7!}{7(5!)}) = 6(\frac{7!}{7(5!)})

Do not distribute the integer through the number before the factorial, and do not cancel the sevens in the numerator and denominator.

\displaystyle 7(5!) \neq 35!

\displaystyle \frac{7!}{7} \neq 1!

Rewrite the numerator in terms so that we can simplify the fraction.

\displaystyle 6(\frac{7!}{7(5!)}) = 6(\frac{7\times 6\times5\times4\times3\times2\times1}{7(5\times4\times3\times2\times1)})

Notice all the constants that we can cancel.  This fraction will reduce to"

\displaystyle 6\times 6 = 36

The answer is:  \displaystyle 36

Example Question #27 : Factorials

Multiply the factorials:  \displaystyle 3!\times (2+3)!\times 0!

Possible Answers:

\displaystyle 120

\displaystyle 1296

\displaystyle 720

\displaystyle 0

\displaystyle 36

Correct answer:

\displaystyle 720

Explanation:

Expand the factorials.  

\displaystyle 3!\times (2+3)!\times 0! = (3\times 2\times 1)\times 5! \times 0!

\displaystyle =(3\times 2\times 1)\times(5\times 4\times 3\times 2\times 1)\times 0!

Zero factorial is a special case.  It is equal to one.

\displaystyle 0!=1

The expression becomes:

\displaystyle =(3\times 2\times 1)\times(5\times 4\times 3\times 2\times 1)

Multiply all the numbers.

\displaystyle =6\times 120= 720

The answer is:  \displaystyle 720

Example Question #28 : Factorials

Simplify the factorials:  \displaystyle \frac{2!(3+3)!}{ 3!\times 6}

Possible Answers:

\displaystyle 20

\displaystyle 40

\displaystyle \frac{1}{3}

\displaystyle \frac{2}{3}

\displaystyle 10

Correct answer:

\displaystyle 40

Explanation:

Simplify the factorials in the numerator first.  

\displaystyle 2!(3+3)! = 2!\cdot 6! =(2\times 1)\cdot (6\times5\times4\times3\times2\times1)

Simplify the denominator.

\displaystyle 3!\times 6 = (3\times 2\times 1) \times 6

Eliminate common terms in the numerator and denominator.

The numerator becomes:  \displaystyle 2 \times 1\times5\times4 = 40

The answer is:  \displaystyle 40

Example Question #31 : Factorials

Simplify the factorials:  \displaystyle (7-4)!\cdot(7!-5!)

Possible Answers:

\displaystyle 29520

\displaystyle 6

\displaystyle 24678720

\displaystyle 12

\displaystyle \textup{The answer is not given.}

Correct answer:

\displaystyle 29520

Explanation:

Evaluate the first term.  Write out the terms of the factorial.

\displaystyle (7-4)! = 3! = 3\times 2 \times 1 = 6

Evaluate the second term.

\displaystyle (7!-5!)

\displaystyle 7! = 7\times6\times5\times4\times3\times2\times1 = 5040

\displaystyle 5!=5\times4\times3\times2\times1 = 120

\displaystyle (7!-5!) = 5040-120 = 4920

Combine the simplified terms.

\displaystyle (7-4)!\cdot(7!-5!) = 6\cdot 4920

The answer is:  \displaystyle 29520

Example Question #32 : Factorials

\displaystyle \frac{15!}{13!}

Possible Answers:

\displaystyle 375

\displaystyle 42

\displaystyle 210

\displaystyle 6227020800

\displaystyle 15

Correct answer:

\displaystyle 210

Explanation:

When you have factorials in the numerator and denominator of a fraction, you can cancel out the common factors between them. It can help to write the problems in expanded form.

\displaystyle \frac{15!}{13!}

\displaystyle \frac{15\cdot 14\cdot 13\cdot 12\cdot 11\cdot 10\cdot 9\cdot 8\cdot 7\cdot 6\cdot 5\cdot 4\cdot 3\cdot 2\cdot 1}{13\cdot 12\cdot 11\cdot 10\cdot 9\cdot 8\cdot 7\cdot 6\cdot 5\cdot 4\cdot 3\cdot 2\cdot 1}

The entire denominator 13 will be cancelled out leaving only

\displaystyle 15\cdot 14

\displaystyle 210

Example Question #33 : Factorials

\displaystyle \frac{7!}{4!}\cdot \frac{5!}{2!}

Possible Answers:

\displaystyle 12600

\displaystyle 1020

\displaystyle 24628

\displaystyle 210

\displaystyle 120

Correct answer:

\displaystyle 12600

Explanation:

Similar factors that are in both the numerator and denominator of a fraction cancel out. It helps to write it in expanded form.

\displaystyle \frac{7!}{4!}\cdot \frac{5!}{2!}

\displaystyle \frac{7\cdot 6\cdot 5\cdot 4\cdot 3\cdot 2\cdot 1}{4\cdot 3\cdot 2\cdot 1}\cdot \frac{5\cdot 4\cdot 3\cdot 2\cdot 1}{2\cdot 1}

\displaystyle 7\cdot 6\cdot 5 \cdot 5\cdot 4\cdot 3

\displaystyle 12600

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