Simplify Base-7 Expression: 7^(2x+1) × 7^(-1) × 7^x

Exponent Rules with Multiple Base-7 Terms

72x+1717x= 7^{2x+1}\cdot7^{-1}\cdot7^x=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:10 Let's simplify this expression!
00:13 When we multiply powers with the same base, we add the exponents. Easy, right?
00:19 This rule works for any number of bases. Isn't that great?
00:26 Alright, let's use this rule in our exercise.
00:29 Now, add up all the exponents carefully.
00:33 Combine all the factors, step by step.
00:44 And there you go! That's the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

72x+1717x= 7^{2x+1}\cdot7^{-1}\cdot7^x=

2

Step-by-step solution

We use the power property to multiply terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n} We apply the property to our expression:

72x+1717x=72x+1+(1)+x=72x+11+x 7^{2x+1}\cdot7^{-1}\cdot7^x=7^{2x+1+(-1)+x}=7^{2x+1-1+x} We simplify the expression we got in the last step:

72x+11+x=73x 7^{2x+1-1+x}=7^{3x} When we add similar terms in the exponent.

Therefore, the correct answer is option d.

3

Final Answer

73x 7^{3x}

Key Points to Remember

Essential concepts to master this topic
  • Rule: When multiplying same bases, add their exponents: aman=am+n a^m \cdot a^n = a^{m+n}
  • Technique: Combine exponents step by step: (2x+1) + (-1) + x = 3x
  • Check: Verify by substituting x=1: 737171=73 7^3 \cdot 7^{-1} \cdot 7^1 = 7^3

Common Mistakes

Avoid these frequent errors
  • Multiplying the exponents instead of adding them
    Don't multiply exponents like (2x+1)(-1)(x) = -2x²-x! This confuses multiplication of powers with powers of powers. Always add exponents when multiplying terms with the same base.

Practice Quiz

Test your knowledge with interactive questions

Simplify the following equation:

\( \)\( 4^5\times4^5= \)

FAQ

Everything you need to know about this question

Why do I add the exponents instead of multiplying them?

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The Product Rule for exponents states that aman=am+n a^m \cdot a^n = a^{m+n} . Think of it this way: 7273 7^2 \cdot 7^3 means (7×7) × (7×7×7) = 7×7×7×7×7 = 75 7^5 , which is 2+3!

What happens when I have a negative exponent like 7⁻¹?

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A negative exponent doesn't change the addition rule! Just treat -1 as a regular number when adding: (2x+1) + (-1) + x = 2x + 1 - 1 + x = 3x.

How do I handle the parentheses in (2x+1)?

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The parentheses show that the entire expression 2x+1 is the exponent. When adding exponents, treat (2x+1) as one unit: (2x+1) + (-1) + x.

Can I simplify this a different way?

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You could rearrange the terms first, like 72x+17x71 7^{2x+1} \cdot 7^x \cdot 7^{-1} , but you'll still get the same answer. The key is always adding all the exponents together!

What if the bases were different numbers?

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If you had something like 7x5x 7^x \cdot 5^x , you cannot combine them using this rule. The Product Rule only works when the bases are identical!

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