Solve: -3 + (-1/2) + (3/8) + 5/8 - Adding Mixed Fractions and Negative Numbers

Fraction Operations with Negative Numbers

3+(12)+(38)+58= -3+(-\frac{1}{2})+(\frac{3}{8})+\frac{5}{8}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:04 Positive times negative always equals negative
00:10 Let's add the fractions to a common denominator
00:17 Let's calculate the numerator
00:26 Let's write the whole fraction as a whole number
00:32 Let's calculate one operation at a time from left to right
00:41 Let's convert from mixed number to fraction
00:54 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

3+(12)+(38)+58= -3+(-\frac{1}{2})+(\frac{3}{8})+\frac{5}{8}=

2

Step-by-step solution

To solve the given problem of adding 3+(12)+38+58 -3 + (-\frac{1}{2}) + \frac{3}{8} + \frac{5}{8} , we will use the following steps:

  • Step 1: Calculate 38+58\frac{3}{8} + \frac{5}{8}
  • Step 2: Subtract 12-\frac{1}{2} from the result of step 1
  • Step 3: Add the final result to 3-3

Now, let us work through each step:

Step 1: Calculate 38+58\frac{3}{8} + \frac{5}{8}. Since these fractions have the same denominator, we simply add their numerators: 3+58=88=1\frac{3 + 5}{8} = \frac{8}{8} = 1.

Step 2: Now we subtract 12-\frac{1}{2} from 1. We can rewrite 11 as 88\frac{8}{8} and 12-\frac{1}{2} as 48-\frac{4}{8} (since their least common denominator is 8). So: 1(12)=88(48)=8+48=128=32.1 - \left(-\frac{1}{2}\right) = \frac{8}{8} - \left(-\frac{4}{8}\right) = \frac{8 + 4}{8} = \frac{12}{8} = \frac{3}{2}.

Step 3: Finally, we add this result to 3-3. 3-3 can be expressed as 62-\frac{6}{2} and 32\frac{3}{2} remains the same: 3+32=62+32=6+32=32=52.-3 + \frac{3}{2} = -\frac{6}{2} + \frac{3}{2} = \frac{-6 + 3}{2} = \frac{-3}{2} = -\frac{5}{2}.

Hence, the solution to the problem is 52-\frac{5}{2}.

3

Final Answer

52 -\frac{5}{2}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Find common denominators before adding or subtracting fractions
  • Technique: Group like operations: 38+58=1 \frac{3}{8} + \frac{5}{8} = 1 first
  • Check: Substitute result back: 3+(12)+1=52 -3 + (-\frac{1}{2}) + 1 = -\frac{5}{2}

Common Mistakes

Avoid these frequent errors
  • Ignoring the negative sign in front of fractions
    Don't treat (12) (-\frac{1}{2}) as positive 12 \frac{1}{2} = wrong sign in final answer! This changes addition to subtraction and gives you a positive result instead of negative. Always keep track of negative signs throughout every step.

Practice Quiz

Test your knowledge with interactive questions

What will be the sign of the result of the next exercise?

\( (-2)\cdot(-4)= \)

FAQ

Everything you need to know about this question

Why do I add the fractions with the same denominator first?

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When fractions have the same denominator, they're easiest to combine! 38+58=88=1 \frac{3}{8} + \frac{5}{8} = \frac{8}{8} = 1 simplifies your work before dealing with different denominators.

How do I handle the negative fraction in parentheses?

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The parentheses around (12) (-\frac{1}{2}) mean you're adding a negative number. This is the same as subtracting 12 \frac{1}{2} , but keep the negative sign visible!

What's the easiest way to find a common denominator?

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Look for the least common multiple (LCM) of your denominators. Here, 2 and 8: since 8 = 2 × 4, the LCM is 8. Convert 12=48 \frac{1}{2} = \frac{4}{8} .

Why is my final answer negative?

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You're adding mostly negative values! 3 -3 and 12 -\frac{1}{2} are both negative, while the positive fractions 38+58=1 \frac{3}{8} + \frac{5}{8} = 1 aren't big enough to make the total positive.

Can I work left to right instead of grouping?

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Yes! Addition is flexible due to the commutative property. However, grouping like operations (same denominators first) usually makes the math easier and reduces errors.

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