Expand the Power: Solving 7^(2x+7) Step by Step

Exponent Rules with Sum Expansion

Expand the following equation:

72x+7= 7^{2x+7}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Identify which expressions are equal to the original expression
00:04 According to the laws of exponents, the multiplication of powers 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'll maintain the base and add the exponents together
00:18 We can observe that this expression is not equal to the original expression
00:27 We will use the same method in order to simplify the remaining expressions
00:31 In this expression the operation is addition and not multiplication, therefore it's not relevant
00:40 This expression is not equal to the original expression
00:55 This expression is equal to the original expression
01:00 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Expand the following equation:

72x+7= 7^{2x+7}=

2

Step-by-step solution

To tackle this problem, we need to expand the expression 72x+7 7^{2x+7} using the properties of exponents:

  • Step 1: Identify the structure of the exponent in the form 2x+7 2x + 7 .
  • Step 2: Recognize this as a sum of two components: 2x 2x and 7 7 .
  • Step 3: Apply the exponent rule am+n=am×an a^{m+n} = a^m \times a^n to separate the expression into two distinct exponent terms.

Now, let's proceed with the solution:

Step 1: Given the exponent is 2x+7 2x + 7 , break it down into individual components:
2x+7=x+x+7 2x + 7 = x + x + 7 .

Step 2: Applying the rule am+n=am×an a^{m+n} = a^m \times a^n :
72x+7=7x+x+7=7x×7x+7 7^{2x+7} = 7^{x+x+7} = 7^x \times 7^{x+7} .

Therefore, the expanded form of the expression is 7x×7x+7 7^x \times 7^{x+7} .

3

Final Answer

7x×7x+7 7^x\times7^{x+7}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Use am+n=am×an a^{m+n} = a^m \times a^n to split sum exponents
  • Technique: Break 2x+7 2x+7 into x+x+7 x+x+7 then apply rule twice
  • Check: Verify 7x×7x+7=7x+(x+7)=72x+7 7^x \times 7^{x+7} = 7^{x+(x+7)} = 7^{2x+7}

Common Mistakes

Avoid these frequent errors
  • Incorrectly splitting the exponent sum
    Don't break 2x+7 2x+7 into 2x 2x and 7 7 = 72x×77 7^{2x} \times 7^7 ! This misses the variable structure. Always recognize that 2x=x+x 2x = x+x to properly separate terms.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why can't I just write 72x×77 7^{2x} \times 7^7 ?

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While this uses the exponent rule correctly, it doesn't match any of the answer choices! The problem wants you to split 2x 2x further into x+x x + x to get 7x×7x+7 7^x \times 7^{x+7} .

How do I know where to split the exponent?

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Look at the answer choices for clues! They show you need two factors with x, so split 2x+7 2x+7 as x+(x+7) x + (x+7) to create 7x×7x+7 7^x \times 7^{x+7} .

What's the difference between 7x+7×72 7^{x+7} \times 7^2 and 7x×7x+7 7^x \times 7^{x+7} ?

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The first splits 2x+7 2x+7 incorrectly as (x+7)+2 (x+7) + 2 , but that doesn't equal 2x+7 2x+7 ! The correct split is x+(x+7)=2x+7 x + (x+7) = 2x+7 .

Can I check my answer by adding the exponents back?

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Yes! For 7x×7x+7 7^x \times 7^{x+7} , add exponents: x+(x+7)=x+x+7=2x+7 x + (x+7) = x + x + 7 = 2x + 7 . This matches the original exponent!

Why is the exponent rule am+n=am×an a^{m+n} = a^m \times a^n true?

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Think of it as repeated multiplication! am+n a^{m+n} means multiply a by itself (m+n) times. This is the same as multiplying a by itself m times, then n more times: am×an a^m \times a^n .

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