Solve: 2(3 + ½×8) - Order of Operations with Mixed Numbers

Order of Operations with Fraction Multiplication

2(3+128)= 2\cdot(3+\frac{1}{2}\cdot8)=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:06 Let's solve this expression step by step.
00:10 First, focus on the parentheses. Always solve those first.
00:16 Next, remember to do multiplication and division before addition and subtraction.
00:22 Now, move the product to the top, into the numerator.
00:26 Let's calculate. Eight divided by two.
00:32 Keep using the order of operations to solve the rest.
00:38 And there you have it! That's the solution.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

2(3+128)= 2\cdot(3+\frac{1}{2}\cdot8)=

2

Step-by-step solution

Let's simplify this expression while following the order of operations which states that exponents come before multiplication and division, which come before addition and subtraction, and that parentheses come before all of these,

We will start by simplifying the expression in parentheses, since multiplication comes before addition, we will first perform the multiplication in the expression, while remembering that multiplying by a fraction means multiplying by the fraction's numerator, then we will perform the division of the fraction (by reducing it), we will complete simplifying the expression in parentheses by performing the addition within them:

2(3+128)=2(3+182)=2(3+)=2(3+4)=27 2\cdot(3+\frac{1}{2}\cdot8)= \\ 2\cdot(3+\frac{1\cdot8}{2})= \\ 2\cdot(3+\frac{\not{8}}{\not{2}})= \\ 2\cdot(3+4)= \\ 2\cdot7 \\ We will finish simplifying the given expression and perform the remaining multiplication:

27=14 2\cdot7= \\ 14 Therefore the correct answer is answer C.

3

Final Answer

14 14

Key Points to Remember

Essential concepts to master this topic
  • PEMDAS Rule: Parentheses first, then multiplication/division before addition
  • Technique: 128=4 \frac{1}{2} \cdot 8 = 4 before adding to 3
  • Check: Work backwards: 14 ÷ 2 = 7, and 7 = 3 + 4 ✓

Common Mistakes

Avoid these frequent errors
  • Working left to right without following order of operations
    Don't calculate 2(3) first = 6, then try to work with fractions! This ignores parentheses completely and gives wrong results like 10. Always simplify inside parentheses first using PEMDAS.

Practice Quiz

Test your knowledge with interactive questions

\( 20\div(4+1)-3= \)

FAQ

Everything you need to know about this question

Why can't I just multiply 2 × 3 first since it's easier?

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The parentheses tell you to solve everything inside them first! If you multiply 2 × 3 = 6 first, you're ignoring the order of operations and will get the wrong answer.

How do I multiply a whole number by a fraction?

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Multiply the whole number by the numerator, then divide by the denominator. So 12×8=82=4 \frac{1}{2} \times 8 = \frac{8}{2} = 4 .

What if I get confused about which operations to do first?

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Remember PEMDAS: Parentheses, Exponents, Multiplication/Division (left to right), Addition/Subtraction (left to right). Always work inside parentheses first!

Can I change the order if it makes the math easier?

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Never! The order of operations is a mathematical rule that must be followed exactly. Changing the order will give you the wrong answer every time.

How do I know if 14 is really the right answer?

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Substitute back: 2(3+12×8)=2(3+4)=2(7)=14 2(3 + \frac{1}{2} \times 8) = 2(3 + 4) = 2(7) = 14 . If your work matches this step-by-step, you're correct!

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