Multiply Powers: Solving 7^9 × 7^1 Using Exponent Rules

Exponent Rules with Same Base Multiplication

79×71= 7^9\times7^1=

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Step-by-step written solution

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1

Understand the problem

79×71= 7^9\times7^1=

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Step-by-step solution

To solve the expression 79×71 7^9 \times 7^1 , we need to apply the rules of exponents, specifically the multiplication of powers rule. According to this rule, when we multiply two powers with the same base, we keep the base and add the exponents together.


  • The expression can be written as am×an=am+n a^m \times a^n = a^{m+n} , where a a is the base and m m and n n are the exponents.
  • In this case, our base a a is 7, and our exponents are 9 and 1.
  • Applying the formula, we have: 79×71=79+1 7^9 \times 7^1 = 7^{9+1} .
  • Simplifying the exponent: 9+1=10 9 + 1 = 10 .

Thus, the expression simplifies to: 710 7^{10} .

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Final Answer

710 7^{10}

Key Points to Remember

Essential concepts to master this topic
  • Product Rule: When multiplying same bases, add the exponents
  • Technique: 79×71=79+1=710 7^9 \times 7^1 = 7^{9+1} = 7^{10}
  • Check: Verify base stays same and exponents were added correctly ✓

Common Mistakes

Avoid these frequent errors
  • Multiplying the exponents instead of adding them
    Don't multiply exponents like 79×71=79×1=79 7^9 \times 7^1 = 7^{9 \times 1} = 7^9 ! This gives the wrong answer because you're applying the wrong rule. Always add exponents when multiplying powers with the same base.

Practice Quiz

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\( 112^0=\text{?} \)

FAQ

Everything you need to know about this question

Why do we add the exponents instead of multiplying them?

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When you multiply powers with the same base, you're actually adding groups of that base together. 79×71 7^9 \times 7^1 means 9 sevens multiplied by 1 seven, giving you 10 sevens total!

What if one of the exponents is 1? Does the rule still apply?

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Yes! The rule works with any exponents, including 1. Remember that 71=7 7^1 = 7 , so you're just adding one more factor of 7 to your multiplication.

How is this different from adding powers like 7^9 + 7^1?

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Great question! Multiplication of powers uses addition of exponents, but addition of powers cannot be simplified this way. 79+71 7^9 + 7^1 stays as is - no exponent rule applies!

What happens if the bases are different, like 7^9 × 3^1?

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The product rule only works with the same base. If bases are different, you cannot combine the exponents. 79×31 7^9 \times 3^1 stays as 79×3 7^9 \times 3 .

Can I use this rule with negative or zero exponents?

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Absolutely! The product rule am×an=am+n a^m \times a^n = a^{m+n} works with any exponents - positive, negative, zero, or even fractions. Just add them together!

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