Calculate 7^9 × 7: Solving a Power Multiplication Problem

Exponent Rules with Same Base Multiplication

79×7= 7^9\times7=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the following problem
00:03 According to the laws of exponents, multiplying exponents with the same base (A)
00:07 equals the same base raised to the sum of the exponents (N+M)
00:11 We will apply this formula to our exercise
00:14 We will add up the exponents and raise to this power
00:17 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

79×7= 7^9\times7=

2

Step-by-step solution

According to the property of powers, when there are two powers with the same base multiplied together, the exponents should be added.

According to the formula:an×am=an+m a^n\times a^m=a^{n+m}

It is important to remember that a number without a power is equivalent to a number raised to 1, not to 0.

Therefore, if we add the exponents:

79+1=710 7^{9+1}=7^{10}

3

Final Answer

710 7^{10}

Key Points to Remember

Essential concepts to master this topic
  • Rule: When multiplying same bases, add the exponents together
  • Technique: Remember 7 = 71 7^1 , so 79×7=79+1 7^9 \times 7 = 7^{9+1}
  • Check: Verify 710 7^{10} follows pattern: same base, exponents added ✓

Common Mistakes

Avoid these frequent errors
  • Adding bases instead of exponents
    Don't add 7 + 7 = 14 and write 149 14^9 ! This ignores exponent rules and gives completely wrong answers. Always keep the same base and add only the exponents when multiplying powers.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why is 7 the same as 71 7^1 ?

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Any number without a visible exponent actually has an invisible exponent of 1. So 7 = 71 7^1 , just like how 5 = 51 5^1 . This is why 79×7=79×71 7^9 \times 7 = 7^9 \times 7^1 .

What if the bases were different numbers?

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The exponent addition rule only works with the same base! For example, 72×32 7^2 \times 3^2 cannot be simplified using this rule. You'd need to calculate each power separately first.

How do I remember when to add vs multiply exponents?

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Add exponents when multiplying same bases: am×an=am+n a^m \times a^n = a^{m+n}
Multiply exponents when raising a power to a power: (am)n=am×n (a^m)^n = a^{m \times n}

Can I just multiply 79×7 7^9 \times 7 by calculating each part?

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You could calculate 79=40,353,607 7^9 = 40,353,607 then multiply by 7, but that's much harder! Using the exponent rule gives you 710 7^{10} instantly and keeps your answer in the simplest form.

What's the difference between 710 7^{10} and 149 14^9 ?

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710 7^{10} means 7 multiplied by itself 10 times, while 149 14^9 means 14 multiplied by itself 9 times. These are completely different values - never add the bases when using exponent rules!

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