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 #31 : Ssat Upper Level Quantitative (Math)

Given: \(\displaystyle a,b,c\) are distinct integers such that:

\(\displaystyle |a|< b < |c|\)

\(\displaystyle a+|b| = |c|\)

Which of the following could be the least of the three?

Possible Answers:

\(\displaystyle a\) or \(\displaystyle b\) only

\(\displaystyle b\) only

\(\displaystyle a\)\(\displaystyle b\), or \(\displaystyle c\)

\(\displaystyle a\) or \(\displaystyle c\) only

\(\displaystyle b\) or \(\displaystyle c\) only

Correct answer:

\(\displaystyle a\) or \(\displaystyle c\) only

Explanation:

\(\displaystyle 0 \le |a|< b < |c|\), which means that \(\displaystyle b\) must be positive. 

If \(\displaystyle a\) is nonnegative, then \(\displaystyle a = |a| < b\). If \(\displaystyle a\) is negative, then it follows that \(\displaystyle a < 0 < b\). Either way, \(\displaystyle a < b\). Therefore, \(\displaystyle b\) cannot be the least. 

We now show that we cannot eliminate \(\displaystyle a\) or \(\displaystyle c\) as the least.

 

For example, if \(\displaystyle a = 4, b= 6, c = 10\), then \(\displaystyle a\) is the least;  we test both statements:

\(\displaystyle |a|< b < |c|\)

\(\displaystyle |4|< 6 < |10|\)

\(\displaystyle 4 < 6< 10\), which is true.

 

\(\displaystyle a+|b| = |c|\)

\(\displaystyle 4+|6| = |10|\)

\(\displaystyle 4+6 =10\), which is also true.

 

If \(\displaystyle a = 4, b= 6, c = - 10\), then \(\displaystyle c\) is the least; we test both statements:

\(\displaystyle |a|< b < |c|\)

\(\displaystyle |4|< 6 < |-10|\)

\(\displaystyle 4 < 6< 10\), which is true.

 

\(\displaystyle a+|b| = |c|\)

\(\displaystyle 4+|6| = |-10|\)

\(\displaystyle 4+6 =10\), which is also true.

 

Therefore, the correct response is \(\displaystyle a\) or \(\displaystyle c\) only.

Example Question #33 : Algebra

\(\displaystyle a\)\(\displaystyle b\), and \(\displaystyle c\) are distinct integers. \(\displaystyle |a|< b\) and \(\displaystyle |b| < c\). Which of the following could be the greatest of the three?

Possible Answers:

\(\displaystyle b\) only

\(\displaystyle a\) only

\(\displaystyle a\)\(\displaystyle b\), or \(\displaystyle c\)

\(\displaystyle c\) only

None of the other responses is correct.

Correct answer:

\(\displaystyle c\) only

Explanation:

\(\displaystyle 0 \le |a|< b\), so \(\displaystyle b\) must be positive. Therefore, since \(\displaystyle 0 \le |b| < c\), equivalently, \(\displaystyle 0 < b < c\), so \(\displaystyle c\) must be positive, and

\(\displaystyle |a|< b < c\)

If \(\displaystyle a\) is negative or zero, it is the least of the three. If \(\displaystyle a\) is positive, then the statement becomes

\(\displaystyle a < b < c\),

and \(\displaystyle a\) is still the least of the three. Therefore, \(\displaystyle c\) must be the greatest of the three.

Example Question #11 : How To Find Absolute Value

Give the solution set:

\(\displaystyle |x- 6| > 17\)

Possible Answers:

\(\displaystyle (-\infty, -11) \cup (23, \infty)\)

\(\displaystyle (-\infty, -11) \cup (11, \infty)\)

\(\displaystyle (-\infty, -23) \cup (23, \infty)\)

\(\displaystyle (-\infty,-23 ) \cup (11, \infty)\)

\(\displaystyle (-\infty,-23 ) \cup (-11, \infty)\)

Correct answer:

\(\displaystyle (-\infty, -11) \cup (23, \infty)\)

Explanation:

If \(\displaystyle |x- 6| > 17\), then either \(\displaystyle x -6 > 17\) or \(\displaystyle x- 6 < -17\). Solve separately:

\(\displaystyle x -6 > 17\)

\(\displaystyle x -6 + 6 > 17 + 6\)

\(\displaystyle x> 23\)

or 

\(\displaystyle x- 6 < -17\)

\(\displaystyle x- 6 + 6< -17 + 6\)

\(\displaystyle x< -11\)

The solution set, in interval notation, is \(\displaystyle (-\infty, -11) \cup (23, \infty)\).

Example Question #31 : Algebra

Define an operation \(\displaystyle \bigstar\) on the real numbers as follows:

If \(\displaystyle a > b\), then \(\displaystyle a \bigstar b = |a + b-1|\)

If \(\displaystyle a = b\), then \(\displaystyle a \bigstar b = 4\)

If \(\displaystyle a< b\), then \(\displaystyle a \bigstar b = |a - b+1|\)

If \(\displaystyle p = 0 \bigstar 5\)\(\displaystyle q = 0 \bigstar 0\), and \(\displaystyle r=0 \bigstar( -5)\)

then which of the following is a true statement?

Possible Answers:

\(\displaystyle p < q = r\)

\(\displaystyle r < p = q\)

\(\displaystyle p = q = r\)

\(\displaystyle q = r< p\)

\(\displaystyle p = q < r\)

Correct answer:

\(\displaystyle p = q < r\)

Explanation:

\(\displaystyle p = 0 \bigstar 5\)

Since \(\displaystyle 0 < 5\), evaluate

\(\displaystyle a \bigstar b = |a - b+1|\), setting  \(\displaystyle a = 0, b=5\):

\(\displaystyle 0 \bigstar 5 = |0 - 5+1|\)

\(\displaystyle 0 \bigstar 5 = |-4| = 4\)

 

\(\displaystyle q = 0 \bigstar 0\)

Since \(\displaystyle 0 = 0\), then select the pattern

\(\displaystyle 0 \bigstar 0 = 4\)

 

\(\displaystyle r=0 \bigstar( -5)\)

Since \(\displaystyle 0 > -5\), evaluate

\(\displaystyle a \bigstar b = |a + b-1|\), setting \(\displaystyle a = 0, b=-5\):

\(\displaystyle 0 \bigstar (-5) = |0 + (-5)-1|\)

\(\displaystyle 0 \bigstar (-5) = |-6| = 6\)

 

\(\displaystyle p = q= 4, r = 6\), so the correct choice is that \(\displaystyle p = q < r\).

 

 

 

Example Question #36 : Algebra

Given: \(\displaystyle m,n,p\) are distinct integers such that:

\(\displaystyle |m|< n < |p|\)

\(\displaystyle |m|+n = p\)

Which of the following could be the least of the three?

Possible Answers:

\(\displaystyle n\) only

\(\displaystyle m\)\(\displaystyle n\), or \(\displaystyle p\)

\(\displaystyle p\) only

\(\displaystyle m\) or \(\displaystyle n\) only

\(\displaystyle m\) only

Correct answer:

\(\displaystyle m\) only

Explanation:

\(\displaystyle 0 \le |m|< n < |p|\), which means that \(\displaystyle n\) must be positive. 

If \(\displaystyle m\) is nonnegative, then \(\displaystyle m = |m| < n\). If \(\displaystyle m\) is negative, then it follows that \(\displaystyle m < 0 < n\). Either way, \(\displaystyle m < n\). Therefore, \(\displaystyle n\) cannot be the least. 

Now examine the statemtn \(\displaystyle |m|+n = p\). If \(\displaystyle m = 0\), then \(\displaystyle n = p\) - but we are given that \(\displaystyle n\) and \(\displaystyle p\) are distinct. Therefore, \(\displaystyle m\) is nonzero, \(\displaystyle |m| > 0\), and 

\(\displaystyle |m| +n > 0 + n\)

and

\(\displaystyle p > n\).

\(\displaystyle p\) cannot be the least either.

Example Question #41 : Ssat Upper Level Quantitative (Math)

\(\displaystyle a\)\(\displaystyle b\), and \(\displaystyle c\) are distinct integers. \(\displaystyle |a|< b\) and \(\displaystyle |b| < c\). Which of the following could be the least of the three?

Possible Answers:

\(\displaystyle a\) or \(\displaystyle b\) only

\(\displaystyle a\) or \(\displaystyle c\) only

\(\displaystyle b\) or \(\displaystyle c\) only

\(\displaystyle a\)\(\displaystyle b\), or \(\displaystyle c\)

None of the other responses is correct.

Correct answer:

None of the other responses is correct.

Explanation:

\(\displaystyle 0 \le |a|< b\), so \(\displaystyle b\) must be positive. Therefore, since \(\displaystyle 0 \le |b| < c\), it follows that \(\displaystyle 0 < b < c\), so \(\displaystyle c\) must be positive, and

\(\displaystyle |a|< b < c\)

If \(\displaystyle a\) is negative or zero, it is the least of the three. If \(\displaystyle a\) is positive, then the statement becomes

\(\displaystyle a < b < c\),

and \(\displaystyle a\) is still the least of the three. Therefore, \(\displaystyle a\) must be the least of the three, and the correct choice is "None of the other responses is correct."

Example Question #11 : How To Find Absolute Value

Give the solution set:

\(\displaystyle |x-7| < 12\)

Possible Answers:

\(\displaystyle (-19, 5)\)

\(\displaystyle (-19,- 5)\)

\(\displaystyle (-5, 5)\)

\(\displaystyle (-5, 19)\)

\(\displaystyle (-19, 19)\)

Correct answer:

\(\displaystyle (-5, 19)\)

Explanation:

When dealing with absolute value bars, it is important to understand that whatever is inside of the absolute value bars can be negative or positive. This means that an inequality can be made.

In this particular case if \(\displaystyle |x-7| < 12\), then, equivalently, 

\(\displaystyle -12 < x-7 < 12\)

From here, isolate the variable by adding seven to each side.

\(\displaystyle -12 + 7< x-7 + 7 < 12 + 7\)

\(\displaystyle -5 < x < 19\)

In interval notation, this is \(\displaystyle (-5, 19)\).

Example Question #13 : How To Find Absolute Value

Solve the following expression for when \(\displaystyle x=7\).

\(\displaystyle \left |4- x^{2}\right |\)

Possible Answers:

\(\displaystyle -53\)

\(\displaystyle 53\)

\(\displaystyle 45\)

\(\displaystyle 49\)

\(\displaystyle -45\)

Correct answer:

\(\displaystyle 45\)

Explanation:

First you plug in \(\displaystyle 7\) for \(\displaystyle x\) and squre it.  

This gives the expression \(\displaystyle 4-49\) which is equal to \(\displaystyle -45\).  

Since the equation is within the absolute value lines, you must make it the absolute value which is the amount of places the number is from zero.  

This makes your answer \(\displaystyle 45\).

Example Question #13 : How To Find Absolute Value

\(\displaystyle \left | x+4 \right | =11\)

Possible Answers:

\(\displaystyle x = -7\) and \(\displaystyle x = 15\)

\(\displaystyle x = -7\) and \(\displaystyle x = -15\)

\(\displaystyle x = 7\) and \(\displaystyle x = 15\)

\(\displaystyle x = 7\) and \(\displaystyle x = -15\)

Correct answer:

\(\displaystyle x = 7\) and \(\displaystyle x = -15\)

Explanation:

The absolute value of a number is its distance from zero.  Absolute value is represented with \(\displaystyle \left | \right |\) or absolute value bars .  To solve this absolute value equation remove the absolute value bars and set the equation equal to positive and negative eleven.

\(\displaystyle x + 4 = 11\)

\(\displaystyle x + 4 - 4 = 11-4\)

\(\displaystyle x = 7\)

 

\(\displaystyle x + 4 = -11\)

\(\displaystyle x + 4 -4 = -11-4\)

\(\displaystyle x = -15\)

 

\(\displaystyle x = 7\) and \(\displaystyle x = -15\) are the two values of \(\displaystyle x\) which make this statement true.

\(\displaystyle \left |7+4 \right | = 11\)

and

\(\displaystyle \left |-15+4 \right | = 11\)

\(\displaystyle \left | -11\right |=11\)

Remember, because Absolute Value measures the distance from zero, the absolute value of a number whether negative or positive is always                    non-negative.

 

Example Question #14 : How To Find Absolute Value

\(\displaystyle - \left | -12\right |\)

Possible Answers:

\(\displaystyle -12\)

\(\displaystyle 0\)

There is no solution.

\(\displaystyle 12\)

Correct answer:

\(\displaystyle -12\)

Explanation:

Absolute value measures distance from that number to the point of origin or zero.

\(\displaystyle \left | -12\right | = 12\)

However, there is a negative sign outside the Absolute value bars, which indicates the multiplication by \(\displaystyle -1\)

\(\displaystyle 12\) becomes \(\displaystyle -12\)

Therefore \(\displaystyle -\left | -12\right | = -12\) is the correct solution.

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