Pre-Algebra : Operations and Properties

Study concepts, example questions & explanations for Pre-Algebra

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Example Questions

Example Question #2 : Associative Property Of Multiplication

Which of the following displays the associative property of multiplication?

Possible Answers:

\displaystyle (a \cdot b) \cdot c = a \cdot (b \cdot c)

\displaystyle a(b \cdot c) = ab \cdot ac

\displaystyle a \cdot 0 = 0

\displaystyle a \cdot b = ab

\displaystyle a \cdot 1 = a

Correct answer:

\displaystyle (a \cdot b) \cdot c = a \cdot (b \cdot c)

Explanation:

The associative property of multiplication states that you can multiply numbers together in any order, and the answer will not change.  Therefore, 

\displaystyle (a \cdot b) \cdot c = a \cdot (b \cdot c)

displays the associative property of multiplication since the two sides are equal no matter which set of parentheses you solve first.

Example Question #1 : High School Math

Simplify the expression.

\displaystyle (-2)(x^2+x-8)

Possible Answers:

\displaystyle 2x^2+2x+16

\displaystyle -2x^2-2x+16

\displaystyle -2x^2-2x-16

\displaystyle 2x^2+2x-16

Correct answer:

\displaystyle -2x^2-2x+16

Explanation:

Use the distributive property to multiply each term of the polynomial by \displaystyle \small -2. Be careful to distribute the negative as well.

\displaystyle (-2)(x^2)+(-2)(x)-(-2)(8)

\displaystyle (-2x^2)+(-2x)-(-16)

\displaystyle -2x^2-2x+16

Example Question #391 : Operations And Properties

Find the value of \displaystyle 2(3-2) -4(2+5-7).

Possible Answers:

6

4

-6

2

-2

Correct answer:

2

Explanation:

We can seperate the problem into two steps:

\displaystyle 2(3-2) = 2(1)=2

\displaystyle -4(2+5-7) = -4(0)=0

We then combine the two parts:

\displaystyle 2+0=2

 

Example Question #1 : Distributive Property

Distribute \displaystyle -4(5x+15y-9).

Possible Answers:

\displaystyle -20x-60y-36

\displaystyle 20x-60y+36

\displaystyle 20x+60y-36

\displaystyle -20x-60y+36

Correct answer:

\displaystyle -20x-60y+36

Explanation:

When distributing with negative numbers we must remember to distribute the negative to all of the variables in the parentheses.

Distribute the \displaystyle -4 through the parentheses by multiplying it with each object in the parentheses to get \displaystyle ((-4)5x+(-4)15y-(-4)9).

Perform the multiplication remembering the positive/negative rules to get \displaystyle -20x-60y+36, our answer.

Example Question #3 : High School Math

Simplify the expression.

\displaystyle (-x+2)(-xy)

Possible Answers:

\displaystyle -x^2y-2xy

\displaystyle -2x^3y^2

\displaystyle 2x^3y^2

\displaystyle x^2y-2xy

Correct answer:

\displaystyle x^2y-2xy

Explanation:

Multiply the mononomial by each term in the binomial, using the distributive property.

\displaystyle (-x+2)(-xy)

\displaystyle (-xy)(-x)+(-xy)(2)

\displaystyle x^2y+(-2xy)

\displaystyle x^2y-2xy

 

Example Question #392 : Operations And Properties

Simplify the expression.

\displaystyle 2x(5+4x+y)

Possible Answers:

\displaystyle 10x+8x^2+2xy

\displaystyle 10x+6x^2+2xy

\displaystyle 10x+8x^2+y

\displaystyle 5+6x+y

\displaystyle 10+8x+2y

Correct answer:

\displaystyle 10x+8x^2+2xy

Explanation:

\displaystyle 2x(5+4x+y)

Use the distributive property to multiply each term by \displaystyle \small 2x.

\displaystyle 2x(5)+2x(4x)+2x(y)

Simplify.

\displaystyle 10x+8x^2+2xy

Example Question #3 : High School Math

Distribute:

\displaystyle -3(-4x+5y-8)

Possible Answers:

\displaystyle 12x-15y+24

\displaystyle 12x+15y-24

\displaystyle -12x+15y-24

\displaystyle 12x+15y+24

\displaystyle x-7y+24

Correct answer:

\displaystyle 12x-15y+24

Explanation:

When distributing with negative numbers we must remember to distribute the negative to all of the terms in the parentheses.

Remember, a negative multiplied by a negative is positive, and a negative multiplied by a positive number is negative.

Distribute the \displaystyle -3 through the parentheses:

\displaystyle -4x(-3)+5y(-3)-8(-3)

Perform the multiplication, remembering the positive/negative rules:

\displaystyle 12x-15y+24

 

Example Question #7 : Apply The Properties Of Operations To Generate Equivalent Expressions: Ccss.Math.Content.6.Ee.A.3

Which of the following is equivalent to \displaystyle -3(2d - 4)?

Possible Answers:

\displaystyle 6d - 12

\displaystyle -6d + 4

\displaystyle -6d - 4

\displaystyle -6d + 12

\displaystyle -6d - 12

Correct answer:

\displaystyle -6d + 12

Explanation:

We need to distribute -3 by multiplying both terms inside the parentheses by -3.:

 \displaystyle -3(2d - 4) = -3(2d) + (-3)(-4).

Now we can multiply and simplify. Remember that multiplying two negative numbers results in a positive number:

\displaystyle -3(2d)+(-3)(-4)= -6d + 12

Example Question #2 : Distributive Property

Expand:

\displaystyle -4x(3x^2-7x+2)

Possible Answers:

\displaystyle 12x^3+28x-8x

\displaystyle -12x^3-28x-8x

\displaystyle 12x^3-28x+8x

\displaystyle -12x^3+28x^{2}-8x

\displaystyle 12x^3+28x-8

Correct answer:

\displaystyle -12x^3+28x^{2}-8x

Explanation:

\displaystyle \small -4x(3x^2-7x+2)

Use the distributive property. Do not forget that the negative sign needs to be distributed as well!

\displaystyle \small \small (-4x)(3x^2)=-12x^3

\displaystyle \small (-4x)(-7x)=28x^2

\displaystyle \small (-4x)(2)=-8x

Add the terms together:

\displaystyle \small -12x^3+28x^2+(-8x)=-12x^3+28x^2-8x

Example Question #391 : Operations And Properties

Distribute:

\displaystyle -5(x+15)

Possible Answers:

\displaystyle -5x+15

\displaystyle -5x-75

\displaystyle -5x-15

\displaystyle -5x+75

\displaystyle 5x+75

Correct answer:

\displaystyle -5x-75

Explanation:

Remember that a negative multiplied by a negative is positive, and a negative multiplied by a positive is negative.

Distribute the \displaystyle -5 through the parentheses by multiplying it by each of the two terms: 

\displaystyle -5x-75

 

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