Pre-Algebra : Operations

Study concepts, example questions & explanations for Pre-Algebra

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Example Questions

Example Question #1 : Operations

Simplify the expression below.

\(\displaystyle x^3+2x+4x^2-(3x-5x^2+2)\)

Possible Answers:

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

\(\displaystyle x^3-9x-x+2\)

\(\displaystyle x^3-x^2-x-2\)

\(\displaystyle x^3+9x^2-x-2\)

Correct answer:

\(\displaystyle x^3+9x^2-x-2\)

Explanation:

First, distribute the negative sign into the parentheses.

\(\displaystyle x^3+2x+4x^2-(3x-5x^2+2)=x^3+2x+4x^2-3x+5x^2-2\)

Next, combine like terms.

\(\displaystyle x^3+9x^2-x-2\)

Note that all operations in this problem are addition and subtraction; there is no need to FOIL or multiply.

Example Question #2 : Order Of Operations

Solve the following problem: \(\displaystyle 17+4\cdot 2-6/2=\)

Possible Answers:

\(\displaystyle 22\)

\(\displaystyle 13\)

\(\displaystyle 18\)

\(\displaystyle 21\)

\(\displaystyle 19\)

Correct answer:

\(\displaystyle 22\)

Explanation:

First, work from left to right completing multiplication and division, then work from left to right completing addition and subtraction. 

\(\displaystyle 17+(2\cdot 4)-(6/2)\)

\(\displaystyle 17+8-3=22\)

Example Question #1 : Order Of Operations

Suppose you know the value of \(\displaystyle N\), and you want to evaluate the expression:

\(\displaystyle 8 \cdot \left (N + 1 \right ) \div N^{2}\)

In which order would you carry out the four operations in the expression?

Possible Answers:

Multiply, add, divide, square

Add, square, multiply, divide

Add, multiply, divide, square

Add, square, divide, multiply

Multiply, divide, add, square

Correct answer:

Add, square, multiply, divide

Explanation:

By order of operations, always carry out any operations within parentheses first; this is the addition.  This removes the parentheses; what remains is a square, a multiplication, and a division. Since there are no more grouping symbols, square next. The multiplication is done next, as multiplications and divisions are performed in left-to-right order.

In summary: Add, square, multiply, divide

Example Question #1 : How To Use The Order Of Operations In Pre Algebra

Suppose you know the value of \(\displaystyle N\), and you want to evaluate the expression:

\(\displaystyle 3 (N + 7)^{2} - 9\)

In which order would you carry out the four operations in the expression?

Possible Answers:

Multiply, square, add, subtract

Add, square, multiply, subtract

Multiply, add, square, subtract

Square, add, multiply, subtract

Square, multiply, add, subtract

Correct answer:

Add, square, multiply, subtract

Explanation:

By order of operations, always carry out any operations within parentheses first; this is the addition. This removes the parentheses; what remains is a square, a multiplication, and a subtraction. This is the correct order in the absence of grouping symbols.

In summary: Add, square, multiply, subtract

Example Question #2 : Order Of Operations

Simplify the expression.

\(\displaystyle 4+2x-1(5^2* 3)\)

Possible Answers:

\(\displaystyle 2x-26\)

\(\displaystyle 8x-75\)

\(\displaystyle 6x-75\)

\(\displaystyle 2x-72\)

\(\displaystyle 2x-71\)

Correct answer:

\(\displaystyle 2x-71\)

Explanation:

The order of operations is parenthesis, exponents, multiplication, division, addition, subtraction (PEMDAS).

\(\displaystyle 4+2x-1(5^2* 3)\)

First, we will evaluate the parentheses. Within the parentheses, we need to solve the exponent, then multiply,

\(\displaystyle 4+2x-1(25* 3)\)

\(\displaystyle 4+2x-1(75)\)

Now that the parenthesis is evaluated, we need to multiply.

\(\displaystyle 4+2x-75\)

Finally, we add and subtract. We can arrange the terms in any order.

\(\displaystyle 2x+4-75\)

\(\displaystyle 2x-71\)

Example Question #1 : Order Of Operations

Simplify:

\(\displaystyle 2\left \{ 3+2[1+(3-2)]\right \}\)

Possible Answers:

\(\displaystyle -9\)

\(\displaystyle -14\)

\(\displaystyle 9\)

\(\displaystyle 14\)

Correct answer:

\(\displaystyle 14\)

Explanation:

Follow the order of operations: parentheses, exponents, multiplication, division, addition, and subtraction. Work from left to right, and start with the innermost nested operations when dealing with multiple parentheses:

\(\displaystyle 2\left \{ 3+2[1+(3-2)]\right \}\)

\(\displaystyle =2\left \{ 3+2[1+(1)]\right \}\)

\(\displaystyle =2\left \{ 3+2[2]\right \}\)

\(\displaystyle =2\left \{ 3+4\right \}\)

\(\displaystyle =2\left \{ 7\right \}\)

\(\displaystyle =14\)

 

Example Question #1 : Operations And Properties

Simplify:

\(\displaystyle 5+[2+3(3-2^2)]\)

Possible Answers:

\(\displaystyle -4\)

\(\displaystyle 4\)

\(\displaystyle -12\)

\(\displaystyle 12\)

Correct answer:

\(\displaystyle 4\)

Explanation:

Follow the order of operations: parentheses, exponents, multiplication, division, addition, and subtraction. Work from left to right, and start with the innermost nested operations when dealing with multiple parentheses:

\(\displaystyle 5+[2+3(3-2^2)]\)

\(\displaystyle =5+[2+3(3-4)]\)

\(\displaystyle =5+[2+3(-1)]\)

\(\displaystyle =5+[2+(-3)]\)

\(\displaystyle =5+[-1]\)

\(\displaystyle =4\)

 

Example Question #1 : Order Of Operations

Simplify:

\(\displaystyle 6^2-[4+3(-6-1)]\)

Possible Answers:

\(\displaystyle -53\)

\(\displaystyle 13\)

\(\displaystyle 53\)

\(\displaystyle -13\)

Correct answer:

\(\displaystyle 53\)

Explanation:

Follow the order of operations: parentheses, exponents, multiplication, division, addition, and subtraction. Work from left to right, and start with the innermost nested operations when dealing with multiple parentheses: 

\(\displaystyle 6^2-[4+3(-6-1)]\)

\(\displaystyle =6^2-[4+3(-7)]\)

\(\displaystyle =6^2-[4+(-21)]\)

\(\displaystyle =6^2-[-17]\)

\(\displaystyle =36+17\)

\(\displaystyle =53\)

Example Question #1 : Operations

Simplify:

\(\displaystyle (3*2+1)-2[3-(4-2)]\)

Possible Answers:

\(\displaystyle -7\)

\(\displaystyle 5\)

\(\displaystyle -5\)

\(\displaystyle 7\)

Correct answer:

\(\displaystyle 5\)

Explanation:

Follow the order of operations: parentheses, exponents, multiplication, division, addition, and subtraction. Work from left to right, and start with the innermost nested operations when dealing with multiple parentheses:

\(\displaystyle (3*2+1)-2[3-(4-2)]\)

\(\displaystyle =(6+1)-2[3-(2)]\)

\(\displaystyle =(7)-2[1]\)

\(\displaystyle =7-2\)

\(\displaystyle =5\)

 

 

 

 

 

 

 

Example Question #4 : Order Of Operations

Simplify:

\(\displaystyle 2^2[2+(3-4)]+[5(2+1-7)]\)

Possible Answers:

\(\displaystyle -11\)

\(\displaystyle 16\)

\(\displaystyle 11\)

\(\displaystyle -16\)

Correct answer:

\(\displaystyle -16\)

Explanation:

Follow the order of operations: parentheses, exponents, multiplication, division, addition, and subtraction. Work from left to right, and start with the innermost nested operations when dealing with multiple parentheses:

\(\displaystyle 2^2[2+(3-4)]+[5(2+1-7)]\)

\(\displaystyle =2^2[2+(-1)]+[5(-4)]\)

\(\displaystyle =2^2[1]+[-20]\)

\(\displaystyle =4[1]+[-20]\)

\(\displaystyle =4-20\)

\(\displaystyle =-16\)

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