Simplify the Expression: 7^(-2) × 7^(-3) × 7^5 Using Laws of Exponents

Exponent Rules with Negative Powers

Insert the corresponding expression:

72×73×75= 7^{-2}\times7^{-3}\times7^5=

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1

Understand the problem

Insert the corresponding expression:

72×73×75= 7^{-2}\times7^{-3}\times7^5=

2

Step-by-step solution

To solve for the expression 72×73×75 7^{-2}\times7^{-3}\times7^5 , we will apply the exponent rule where we add the exponents when multiplying powers with the same base.

Step 1: Identify the exponents in the expression:

  • First term has exponent 2-2
  • Second term has exponent 3-3
  • Third term has exponent 55

Step 2: Use the exponent rule am×an=am+n a^m \times a^n = a^{m+n}

We add the exponents: 2+(3)+5-2 + (-3) + 5.

Step 3: Calculate the sum of the exponents:

2+(3)+5=23+5=5+5=0-2 + (-3) + 5 = -2 - 3 + 5 = -5 + 5 = 0

Therefore, the simplified expression is 70 7^0 .

However, the task specifically asks us to represent the step incorporating the exponent change. In this step, it should reflect as:

723+5 7^{-2-3+5} , indicating the addition process before simplification to 0. Let's consider the provided choices:

The correct choice from the list provided that matches our transformation is:

  • Choice 4: 723+5 7^{-2-3+5}

Hence, the expression 72×73×75 7^{-2}\times7^{-3}\times7^5 can be represented by the expression 723+5 7^{-2-3+5} .

Therefore, the correct representation is 723+5 7^{-2-3+5} .

3

Final Answer

723+5 7^{-2-3+5}

Key Points to Remember

Essential concepts to master this topic
  • Rule: When multiplying same bases, add all exponents together
  • Technique: Write 72×73×75=72+(3)+5 7^{-2} \times 7^{-3} \times 7^5 = 7^{-2+(-3)+5}
  • Check: Verify the sum: -2 + (-3) + 5 = 0, so answer is 70=1 7^0 = 1

Common Mistakes

Avoid these frequent errors
  • Adding exponents incorrectly with negative signs
    Don't write 72+3+5 7^{2+3+5} by ignoring negative signs = wrong base power! Negative exponents stay negative when adding. Always keep the negative signs: 723+5 7^{-2-3+5} .

Practice Quiz

Test your knowledge with interactive questions

\( (3\times4\times5)^4= \)

FAQ

Everything you need to know about this question

Why do I add the exponents instead of multiplying them?

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The multiplication rule for exponents states that am×an=am+n a^m \times a^n = a^{m+n} . You only multiply exponents when raising a power to a power, like (am)n=amn (a^m)^n = a^{mn} .

How do I handle the negative exponents when adding?

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Treat negative exponents just like negative numbers in addition. So 2+(3)+5 -2 + (-3) + 5 becomes 23+5=0 -2 - 3 + 5 = 0 . Keep the negative signs throughout your work!

What does 70 7^0 equal?

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Any number (except 0) raised to the power of 0 equals 1. So 70=1 7^0 = 1 , 1000=1 100^0 = 1 , even (5)0=1 (-5)^0 = 1 !

Why is the answer 723+5 7^{-2-3+5} and not 72+3+5 7^{2+3+5} ?

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Because the original expression has negative exponents: 72 7^{-2} and 73 7^{-3} . You must preserve these negative signs when adding: 2+(3)+5 -2 + (-3) + 5 .

Can I simplify this further than 723+5 7^{-2-3+5} ?

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Yes! Since 23+5=0 -2 - 3 + 5 = 0 , you can simplify to 70=1 7^0 = 1 . But the question asks for the expression form showing the exponent addition step.

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