SSAT Upper Level Math : How to find absolute value

Study concepts, example questions & explanations for SSAT Upper Level Math

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Example Questions

Example Question #1 : Absolute Value

Evaluate for \displaystyle x = 2:

\displaystyle \left | 2x - 18 \right | + \left | 3x - 7 \right |

Possible Answers:

\displaystyle 21

\displaystyle 23

\displaystyle 27

\displaystyle 15

\displaystyle 13

Correct answer:

\displaystyle 15

Explanation:

\displaystyle \left | 2x -18 \right | + \left | 3x - 7 \right |

\displaystyle = \left | 2 \cdot 2 - 18 \right | + \left | 3 \cdot 2 - 7 \right |

\displaystyle = \left | 4 - 18 \right | + \left | 6 - 7 \right |

\displaystyle = \left | -14 \right | + \left | -1 \right |

\displaystyle =14 + 1 = 15

Example Question #1 : How To Find Absolute Value

Evaluate for \displaystyle x = 0.6 :

\displaystyle \left | 4x - 1.4 \right | + \left | x^{2} - 1 \right |

Possible Answers:

\displaystyle 0.64

\displaystyle 0.36

\displaystyle 1.36

\displaystyle 2.36

\displaystyle 1.64

Correct answer:

\displaystyle 1.64

Explanation:

Substitute 0.6 for \displaystyle x :

\displaystyle \left | 4x - 1.4 \right | + \left | x^{2} - 1 \right |

\displaystyle = \left | 4 \cdot 0.6 - 1.4 \right | + \left | 0.6^{2} - 1 \right |

\displaystyle = \left | 2.4 - 1.4 \right | + \left | 0.36 - 1 \right |

\displaystyle = \left | 1 \right | + \left | -0.64 \right |

\displaystyle =1 + 0.64

\displaystyle = 1.64

Example Question #3 : Absolute Value

Evaluate for \displaystyle x = 0.6:

\displaystyle \left |0.5 x - 0.7 \right | - \left |0.6 x - 0.4 \right |

Possible Answers:

\displaystyle 0.96

\displaystyle 0.44

\displaystyle 1.04

\displaystyle 0.76

\displaystyle 0.36

Correct answer:

\displaystyle 0.36

Explanation:

Substitute \displaystyle x = 0.6.

\displaystyle \left |0.5 x - 0.7 \right | - \left |0.6 x - 0.4 \right |

\displaystyle = \left |0.5 \cdot 0.6 - 0.7 \right | - \left |0.6 \cdot 0.6 - 0.4 \right |

\displaystyle = \left |0.3- 0.7 \right | - \left |0.36 - 0.4 \right |

\displaystyle = \left |-0.4 \right | - \left | - 0.04 \right |

\displaystyle = 0.4 - 0.04 = 0.36

Example Question #1 : How To Find Absolute Value

Which of the following sentences is represented by the equation 

\displaystyle | x + 7 | = x - 3

Possible Answers:

The sum of three and the absolute value of the sum of a number is three greater than the number.

The sum of three and the absolute value of the sum of a number is three less than the number.

The absolute value of the sum of a number and seven is three greater than the number.

The absolute value of the sum of a number and seven is three less than the number.

None of the other responses are correct.

Correct answer:

The absolute value of the sum of a number and seven is three less than the number.

Explanation:

\displaystyle | x + 7 | is the absolute value of \displaystyle x+ 7, which in turn is the sum of a number and  seven and a number. Therefore, \displaystyle | x + 7 | can be written as "the absolute value of the sum of a number and seven". Since it is equal to \displaystyle x - 3, it is three less than the number, so the equation that corresponds to the sentence is 

"The absolute value of the sum of a number and seven is three less than the number."

Example Question #4 : Absolute Value

Define \displaystyle f(x) = |3x - |x^{2}- 7|\; |

Evaluate \displaystyle f(2).

Possible Answers:

\displaystyle 3

\displaystyle 9

None of the other responses is correct.

\displaystyle 5

\displaystyle 17

Correct answer:

\displaystyle 3

Explanation:

\displaystyle f(x) = |3x - |x^{2}- 7|\; |

\displaystyle f(2) = |3 \cdot 2 - |2^{2}- 7|\; |

\displaystyle = |3 \cdot 2 - |4- 7|\; |

\displaystyle = |3 \cdot 2 - |-3|\; |

\displaystyle = |3 \cdot 2 -3 |

\displaystyle = |6 -3 |

\displaystyle = | 3 |

\displaystyle = 3

Example Question #4 : Absolute Value

Define an operation  as follows:

For all real numbers \displaystyle a,b,

Evaluate: .

Possible Answers:

None of the other responses is correct.

\displaystyle 0

\displaystyle 1 \frac{1}{8}

The expression is undefined.

\displaystyle \frac{5}{8}

Correct answer:

\displaystyle 1 \frac{1}{8}

Explanation:

, or, equivalently,

\displaystyle = \frac{9}{5} \div \left ( \frac{4}{5} +\frac{4}{5} \right )

\displaystyle = \frac{9}{5} \div \frac{8}{5}

\displaystyle = \frac{9}{5} \times \frac{5}{8}

\displaystyle = \frac{9}{8}

\displaystyle =1 \frac{1}{8}

Example Question #11 : How To Find Absolute Value

Define \displaystyle p(x) = \frac{\left |x+2 \right |-1}{\left |x+1 \right |-2}.

Evaluate \displaystyle p \left (-1 \frac{1}{5} \right ).

Possible Answers:

\displaystyle 1

\displaystyle \frac{1}{11}

\displaystyle \frac{1} {9}

\displaystyle -\frac{1}{11}

\displaystyle -\frac{1} {9}

Correct answer:

\displaystyle \frac{1} {9}

Explanation:

\displaystyle p(x) = \frac{\left |x+2 \right |-1}{\left |x+1 \right |-2}, or, equivalently,

\displaystyle p(x) =\left ( \left |x+2 \right |-1 \right ) \div \left ( \left |x+1 \right |-2 \right )

\displaystyle p\left (-1 \frac{1}{5} \right )=\left ( \left |-1 \frac{1}{5}+2 \right |-1 \right ) \div \left ( \left |-1 \frac{1}{5}+1 \right |-2 \right )

\displaystyle =\left ( \left | \frac{4}{5} \right |-1 \right ) \div \left ( \left |- \frac{1}{5} \right |-2 \right )

\displaystyle =\left ( \frac{4}{5} -1 \right ) \div \left ( \frac{1}{5} -2 \right )

\displaystyle = - \frac{1}{5} \div \left ( - \frac{9}{5} \right )

\displaystyle = \frac{1}{5} \div \frac{9}{5}

\displaystyle = \frac{1}{5} \times \frac{5}{9}

\displaystyle = \frac{1} {9}

Example Question #1 : Absolute Value

Define an operation \displaystyle \triangleright as follows:

For all real numbers \displaystyle a,b,

\displaystyle a \triangleright b = \left | a- \frac{1}{2}b\right | + \left | \frac{1}{2} a+b\right |

Evaluate \displaystyle \frac{1}{3} \triangleright 4.

Possible Answers:

\displaystyle \text{None of the other responses are correct.}

\displaystyle 5 \frac{5}{6}

\displaystyle 1\frac{1}{2}

\displaystyle 2\frac{1}{2}

\displaystyle 6\frac{1}{2}

Correct answer:

\displaystyle 5 \frac{5}{6}

Explanation:

\displaystyle a \triangleright b = \left | a- \frac{1}{2}b\right | + \left | \frac{1}{2} a+b\right |

\displaystyle \frac{1}{3} \triangleright 4 = \left | \frac{1}{3} - \frac{1}{2} \cdot 4\right | + \left | \frac{1}{2} \cdot \frac{1}{3} +4\right |

\displaystyle = \left | \frac{1}{3} - 2\right | + \left | \frac{1}{6} +4\right |

\displaystyle = \left | -1 \frac{2}{3} \right | + \left | 4 \frac{1}{6} \right |

\displaystyle = 1 \frac{2}{3} + 4 \frac{1}{6}

\displaystyle = 5 \frac{5}{6}

Example Question #31 : Ssat Upper Level Quantitative (Math)

Define \displaystyle g(x)= \left | \left | 1,000- \sqrt{x}\right | - x^{3} \right |.

Evaluate \displaystyle g(16).

Possible Answers:

Correct answer:

Explanation:

\displaystyle g(x)= \left | \left | 1,000- \sqrt{x}\right | - x^{3} \right |

\displaystyle g(16)= \left | \left | 1,000- \sqrt{16}\right | - 16^{3} \right |

\displaystyle = \left | \left | 1,000- 4 \right | - 16^{3} \right |

\displaystyle = \left | \left | 996 \right | - 16^{3} \right |

\displaystyle = \left | 996 - 16^{3} \right |

\displaystyle = \left | 996 - 4,096 \right |

\displaystyle = \left | -3,100 \right |

\displaystyle =3,100

Example Question #1 : How To Find Absolute Value

Define an operation  as follows:

For all real numbers \displaystyle a,b,

Evaluate 

Possible Answers:

\displaystyle 11

\displaystyle 27

\displaystyle 17

\displaystyle -11

Both \displaystyle 11 and \displaystyle -11

Correct answer:

\displaystyle 11

Explanation:

\displaystyle = \left |-8- (-14) + 5 \right |

\displaystyle = \left |-8+14 + 5 \right |

\displaystyle = \left |11 \right |

\displaystyle = 11

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