Simplify (9×7)^2x / (7×9)^2y: Comparing Exponential Expressions

Exponent Laws with Identical Bases

Insert the corresponding expression:

(9×7)2x(7×9)2y= \frac{\left(9\times7\right)^{2x}}{\left(7\times9\right)^{2y}}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:12 Let's keep it simple.
00:15 In multiplication, changing the order of numbers doesn't matter.
00:19 We'll use this idea and switch the order of numbers in our exercise.
00:27 Let's apply the rule for dividing powers.
00:30 If you have A to the power of N divided by A to the power of M,
00:35 it equals A to the power of M minus N.
00:39 This formula will help us in our problem.
00:43 And that's how we solve this question.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Insert the corresponding expression:

(9×7)2x(7×9)2y= \frac{\left(9\times7\right)^{2x}}{\left(7\times9\right)^{2y}}=

2

Step-by-step solution

To solve the equation, you're required to simplify the expression (9×7)2x(7×9)2y \frac{\left(9\times7\right)^{2x}}{\left(7\times9\right)^{2y}} . This expression contains powers of quotients, and you can apply the properties of exponents to simplify it.

Let's go through the solution step by step:

  • Both the numerator and the denominator are raised to some powers. Notice that the base of both the numerator and the denominator is (9×7) (9 \times 7) , since 9×7=63 9 \times 7 = 63 and 7×9=63 7 \times 9 = 63 .
  • Therefore, you can rewrite the expression as (63)2x(63)2y \frac{(63)^{2x}}{(63)^{2y}} .
  • According to the property of exponents, aman=amn \frac{a^m}{a^n} = a^{m-n} , where a a is a non-zero number. Apply this rule:
  • (63)2x(63)2y=(63)2x2y \frac{(63)^{2x}}{(63)^{2y}} = (63)^{2x-2y}

With the simplification completed, you get (63)2x2y \left(63\right)^{2x-2y} .

Finally, substitute back 63 63 for 9×7 9 \times 7 , and you can express the result as (9×7)2x2y \left(9 \times 7\right)^{2x-2y} .

The solution to the question is: (9×7)2x2y \left(9\times7\right)^{2x-2y} .

3

Final Answer

(9×7)2x2y \left(9\times7\right)^{2x-2y}

Key Points to Remember

Essential concepts to master this topic
  • Rule: When dividing powers with same base, subtract exponents
  • Technique: Recognize 9×7 = 7×9, so (63)2x(63)2y=(63)2x2y \frac{(63)^{2x}}{(63)^{2y}} = (63)^{2x-2y}
  • Check: If x=3, y=1, then (9×7)62=(9×7)4 (9×7)^{6-2} = (9×7)^4

Common Mistakes

Avoid these frequent errors
  • Treating different-looking bases as different
    Don't assume (9×7) and (7×9) are different bases = wrong simplified form! Multiplication is commutative, so 9×7 = 63 and 7×9 = 63 are identical. Always recognize that identical values create the same base for exponent division.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why are (9×7) and (7×9) considered the same base?

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Because multiplication is commutative! This means 9×7 = 63 and 7×9 = 63. Since both equal the same number, they're identical bases for the exponent rule.

What's the exponent rule for division again?

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When dividing powers with the same base: aman=amn \frac{a^m}{a^n} = a^{m-n} . You subtract the bottom exponent from the top exponent!

Can I just cancel out the (9×7) terms?

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No! You can't cancel bases when they have different exponents. You must use the exponent division rule: subtract the exponents to get (9×7)2x2y (9×7)^{2x-2y} .

What if the exponents were the same?

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If both exponents were equal, like (9×7)2x(9×7)2x \frac{(9×7)^{2x}}{(9×7)^{2x}} , then the result would be (9×7)2x2x=(9×7)0=1 (9×7)^{2x-2x} = (9×7)^0 = 1 !

Do I need to calculate 9×7 = 63?

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Not necessarily! You can work with (9×7)2x2y (9×7)^{2x-2y} as your final answer. The important part is recognizing the bases are identical and applying the exponent rule correctly.

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