Solve (-6)·(?5)=30: Determining the Correct Multiplication Sign

Integer Sign Rules with Missing Factors

Fill in the corresponding sign for the following question

(6)(?5)=30 (-6)\cdot(?5)=30

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Complete the appropriate sign
00:03 The solution is positive, so we want a sign that results in a positive outcome
00:08 Negative times negative always equals positive
00:11 Therefore, the appropriate sign is negative
00:17 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

Fill in the corresponding sign for the following question

(6)(?5)=30 (-6)\cdot(?5)=30

2

Step-by-step solution

We should first consider which value we need to multiply a negative number by in order to get a positive number.

Let's remember the rule:

(x)×(x)=+x (-x)\times(-x)=+x

Therefore, the answer is:

5 -5

3

Final Answer

() (-)

Key Points to Remember

Essential concepts to master this topic
  • Rule: Negative times negative equals positive result
  • Technique: (-6) × (-5) = +30, so missing sign is negative
  • Check: Verify: (-6) × (-5) = +30 matches the given equation ✓

Common Mistakes

Avoid these frequent errors
  • Choosing positive sign because the result is positive
    Don't think (+5) because the answer is positive 30 = wrong reasoning! This ignores that we already have a negative factor (-6). Always remember: negative × negative = positive, so we need (-5) to get +30.

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

\( (+6)\cdot(+9)= \)

FAQ

Everything you need to know about this question

Why can't the missing number be positive if the answer is positive?

+

Because we already have (-6) as one factor! If we used (+5), we'd get: (-6) × (+5) = -30, not +30. We need two negatives to make a positive result.

What's the rule for multiplying positive and negative numbers?

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Same signs = positive result
• (+) × (+) = (+)
• (-) × (-) = (+)

Different signs = negative result
• (+) × (-) = (-)
• (-) × (+) = (-)

How do I remember which sign to use?

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Think: "What do I need to multiply (-6) by to get +30?" Since the result is positive and one factor is negative, the other factor must also be negative to make both signs the same.

What if I'm still confused about the signs?

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Try both options! Test (+5): (-6) × (+5) = -30 ❌
Test (-5): (-6) × (-5) = +30 ✓
Only one gives the correct answer!

Is there a trick to avoid sign errors?

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Count the negative signs! An even number of negatives gives a positive result. An odd number gives a negative result. Here: (-6) × (?) = +30 needs 2 negatives total.

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