GED Math : GED Math

Study concepts, example questions & explanations for GED Math

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Example Questions

Example Question #2 : Operations With Negative Numbers

Evaluate:

\(\displaystyle 3.7 - 9.17\)

Do not use a calculator.

Possible Answers:

\(\displaystyle -8.8\)

\(\displaystyle -6.67\)

\(\displaystyle -5.47\)

\(\displaystyle -6.53\)

Correct answer:

\(\displaystyle -5.47\)

Explanation:

To subtract a larger positive number from a smaller positive number, do the reverse, then affix a negative symbol, as demonstrated here:

\(\displaystyle 3.7 - 9.17 = 3.7 +\left ( - 9.17 \right ) = - (9.17-3.7)\)

So subtract 3.7 from 9.17:

\(\displaystyle \begin{matrix} \; \; 9.17\\ \underline{-3.70}\\ \; \; 5.47 \end{matrix}\)

Since the answer must be negative, it is \(\displaystyle -5.47\).

Example Question #2 : Operations With Negative Numbers

Evaluate:

\(\displaystyle -13 \left ( - 24 \right )\)

Do not use a calculator.

Possible Answers:

\(\displaystyle -11\)

\(\displaystyle -312\)

\(\displaystyle 312\)

\(\displaystyle 11\)

Correct answer:

\(\displaystyle 312\)

Explanation:

To obtain the product of two numbers of unlike sign, multiply their absolute values:

\(\displaystyle -13 \left ( - 24 \right ) = 13 \times 24 = 312\)

The product will remain positive.

Example Question #3 : Operations With Negative Numbers

Evaluate \(\displaystyle 4x + 11\) for \(\displaystyle x = -7\). Do NOT use a calculator.

Possible Answers:

\(\displaystyle -17\)

\(\displaystyle -39\)

\(\displaystyle 16\)

\(\displaystyle 8\)

Correct answer:

\(\displaystyle -17\)

Explanation:

Substitute \(\displaystyle - 7\) for \(\displaystyle x\) in the expression.

\(\displaystyle 4x + 11\)

\(\displaystyle = 4 \cdot (-7 )+ 11\)

\(\displaystyle = (-4 \cdot 7) + 11\)

\(\displaystyle =-28 + 11\)

\(\displaystyle = -(28 - 11)\)

\(\displaystyle = -17\)

Example Question #4 : Operations With Negative Numbers

Evaluate: 

\(\displaystyle -17 - (-62)\)

Do not use a calculator.

Possible Answers:

\(\displaystyle 45\)

\(\displaystyle 79\)

\(\displaystyle -45\)

\(\displaystyle -79\)

Correct answer:

\(\displaystyle 45\)

Explanation:

To subtract with negative numbers, change to an addition and make the second number its opposite:

\(\displaystyle -17 - (-62)\)

\(\displaystyle = -17 +62\)

To add two numbers of unlike sign, if the positive has the greater absolute value, simply subtract the absolute values.

\(\displaystyle -17 +62\)

\(\displaystyle =62-17 = 45\)

The answer is 45.

Example Question #5 : Operations With Negative Numbers

Evaluate:

\(\displaystyle - 6 \cdot 16\)

Do NOT use a calculator.

Possible Answers:

\(\displaystyle -10\)

\(\displaystyle -22\)

\(\displaystyle -96\)

\(\displaystyle 10\)

Correct answer:

\(\displaystyle -96\)

Explanation:

To obtain the product of two numbers of unlike sign, multiply their absolute values and affix a negative symbol.

\(\displaystyle - 6 \cdot 16 = -(6\cdot 16) = -96\)

Example Question #6 : Operations With Negative Numbers

Which of these is not equal to \(\displaystyle -9\) ?

Do not use a calculator.

Possible Answers:

\(\displaystyle \frac{-27}{-3}\)

The reciprocal of \(\displaystyle - \frac{1}{9}\)

\(\displaystyle \frac{-45}{5}\)

\(\displaystyle \frac{36}{-4}\)

Correct answer:

\(\displaystyle \frac{-27}{-3}\)

Explanation:

Only one of the choices is positive - \(\displaystyle \frac{-27}{-3}\), which is the quotient of two negative numbers. This must be the correct response.

Example Question #7 : Operations With Negative Numbers

Evaluate:

\(\displaystyle | 24 + (-34) | - 6\)

Possible Answers:

\(\displaystyle 52\)

\(\displaystyle 64\)

\(\displaystyle 4\)

\(\displaystyle 16\)

Correct answer:

\(\displaystyle 4\)

Explanation:

\(\displaystyle | 24 + (-34) | - 6\)

\(\displaystyle = | -( 34-24) | - 6\)

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

\(\displaystyle = 10 - 6\)

\(\displaystyle =4\)

Example Question #8 : Operations With Negative Numbers

How many of these statements are correct?

I) \(\displaystyle 0.5 \leq |- 0.5 |\)

II) \(\displaystyle 0 \leq |- 0.5 |\)

III) \(\displaystyle -0.5 \leq |- 0.5 |\)

Possible Answers:

One

None

Two

Three

Correct answer:

Three

Explanation:

The absolute value of a negative number can be determined by removing the negative symbol, so \(\displaystyle |-0.5 | = 0.5\). Of the three numbers \(\displaystyle \left \{ -0.5, 0, 0.5 \right \}\), all are less than or equal to 0.5. 

Example Question #9 : Operations With Negative Numbers

Raise \(\displaystyle -11\) to the third power.

Do not use a calculator.

Possible Answers:

\(\displaystyle -33\)

\(\displaystyle 33\)

\(\displaystyle 1,331\)

\(\displaystyle -1,331\)

Correct answer:

\(\displaystyle -1,331\)

Explanation:

An odd power of a negative number is negative, so take 11 to the third power,  then affix a negaitve symbol.

\(\displaystyle 11^{3} = 11 \times 11 \times 11 = 121 \times 11 = 1,331\)

The result must be negative, so the correct response is \(\displaystyle -1,331\).

Example Question #11 : Operations With Negative Numbers

Order from least to greatest:

\(\displaystyle | -10 |, |-5| , | 4| , |9|\)

Possible Answers:

\(\displaystyle | -10 | ,|9| ,|-5| ,| 4|\)

\(\displaystyle | -10 |, |-5| , | 4| , |9|\)

\(\displaystyle |9| , | 4| ,|-5| ,| -10 |\)

\(\displaystyle | 4| ,|-5| ,|9| ,| -10 |\)

Correct answer:

\(\displaystyle | 4| ,|-5| ,|9| ,| -10 |\)

Explanation:

The absolute value of a nonnegative number is the number itself; the absolute value of a negative number is obtained by removing the negative symbol. Therefore:

\(\displaystyle | 4| = 4\)

\(\displaystyle |-5| = 5\)

\(\displaystyle |9| = 9\)

\(\displaystyle | -10 | = 10\)

In ascening order, the numbers are \(\displaystyle | 4| ,|-5| ,|9| ,| -10 |\).

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