Algebra 1 : How to multiply integers

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #1 : How To Multiply Integers

Evaluate 5x + 3y when x = 7 and y = 9.

Possible Answers:

66

–62

–66

8

62

Correct answer:

62

Explanation:

Plug in 7 for x and 5 for y, giving you 5(7) + 3(9). This is equal to 35 + 27, which equals 62.

5x + 3y

5(7) + 3(9)

35 + 27 = 62

Example Question #71 : Real Numbers

A plane flies at a rate of 210mi/h. If the plane has flown for five hours, how many miles has it traveled?

Possible Answers:

840mi

215mi

1000mi

42mi

1050mi

Correct answer:

1050mi

Explanation:

Multiply the rate of travel (210 mi/hr) by the time traveled (5 hours), and you get the total distance, 1050 miles.

distance = rate * time

distance = (210mi/hr)(5hr)

distance = 1050mi

Example Question #72 : Real Numbers

Find the volume of a cube that is five feet on each side.

Possible Answers:

25ft3

125ft3

15ft3

5ft3

10ft3

Correct answer:

125ft3

Explanation:

To find the volume of a cube, you cube the side length, raising it to the thrid power. 5 cubed is 125.

(5ft)3 = 5ft*5ft*5ft = 125ft3

Example Question #1 : How To Multiply Integers

What is the square root of 81? 

Possible Answers:

27

9

40.5

3

–9

Correct answer:

9

Explanation:

9 * 9 = 81, and thus 9 is the square root of 81. It is true that (–9) * (–9) = 81, but it is a convention that "the square root" refers to the positive value.  Had the question asked for "a square root" or "the square roots" of 81, –9 would be acceptable.

Example Question #1 : How To Multiply Integers

What is (–16) * (–2)? 

Possible Answers:

64

–8

–32

32

8

Correct answer:

32

Explanation:

When multiplying two negative numbers, the negatives cancel each other out, leaving a positive solution, thus, we can think of (–16)(–2) as (16)(2), which is 32.

(–16) * (–2)

(–1)(16) * (–1)(2)

(–1)(–1) * (16)(2)

(1) * (16)(2)

16 * 2

32

Example Question #5 : How To Multiply Integers

Solve:

\displaystyle \frac{(3\cdot 7-4)}{2\cdot 4^3}

Possible Answers:

\displaystyle 7.5

\displaystyle \frac{9}{128}

\displaystyle \frac{17}{128}

None of the available answers

\displaystyle 0.13

Correct answer:

\displaystyle \frac{17}{128}

Explanation:

\displaystyle \frac{(3\cdot 7-4)}{2\cdot 4^3}

\displaystyle \frac{(3\cdot 7-4)}{2\cdot 64}

\displaystyle \frac{(21-4)}{128}

\displaystyle \frac{17}{128}

 

Example Question #71 : Real Numbers

If \displaystyle p is an integer, which of the following must be odd?

Possible Answers:

\displaystyle 3p+1

\displaystyle p-1

\displaystyle 7p

\displaystyle 2p+1

\displaystyle 3p

Correct answer:

\displaystyle 2p+1

Explanation:

While all of the answers could result in an odd answer, only \displaystyle 2p+1 guarantees an odd answer.  Since any integer multiplied by 2 is even, adding 1 will always give the next consecutive odd integer.

Example Question #2 : How To Multiply Integers

What is \displaystyle (9) * (-7) ?

Possible Answers:

\displaystyle 63

\displaystyle -56

\displaystyle 2

\displaystyle -16

\displaystyle -63

Correct answer:

\displaystyle -63

Explanation:

Multiply the absolute values to get the magnitude of the answer.

\displaystyle 9*7=63

Remember the following rules:

Positive * negative = negative

Positive * positive = positive

Negative * negative = positive

Since we are dealing with a positive and a negative, our answer will be negative.

\displaystyle 9*-7=-63

Example Question #1 : How To Multiply Integers

\displaystyle 100-30\times4+25\times 2= ?

Possible Answers:

\displaystyle 90

\displaystyle 30

\displaystyle 230

\displaystyle 610

\displaystyle 10

Correct answer:

\displaystyle 30

Explanation:

\displaystyle \textup{Order of operations: Perform multiplication functions before addition/subtraction.}

\displaystyle 100-30\times4+25\times 2= \;\;100-120+50\;\;\;= \;\;\;30

Example Question #4 : How To Multiply Integers

\displaystyle \frac{\left ( 2-4 \right )^{3}}{3\times 6}=

Possible Answers:

\displaystyle -\frac{4}{9}

\displaystyle \frac{9}{4}

\displaystyle \frac{4}{9}

\displaystyle -\frac{9}{4}

Correct answer:

\displaystyle -\frac{4}{9}

Explanation:

\displaystyle \frac{\left ( 2-4^ \right )^{3}}{3\times 6}= \frac{-2^{3}}{18}=\frac{-8}{18}=\frac{4}{9}

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