Mastering Negative Exponents: Simplifying (ax/b)⁻ʐ

Negative Exponents with Multi-Variable Expressions

(axb)z=? (\frac{ax}{b})^{-z}=\text{?}

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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 When raising a fraction to a power, both the numerator and the denominator are raised to the power
00:08 We will apply this formula to our exercise
00:20 Let's break it down into a multiplication and a fraction
00:23 In order to remove the negative exponent
00:27 Flip both the numerator and the denominator and the exponent will become positive
00:30 We will apply this formula to our exercise
00:42 When there's a power on a product of multiple terms, each factor is raised to that power
00:49 We will apply this formula to our exercise
00:59 We will use the commutative law to arrange the exercise
01:02 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

(axb)z=? (\frac{ax}{b})^{-z}=\text{?}

2

Step-by-step solution

To solve this problem, we first recognize that we have the expression (axb)z (\frac{ax}{b})^{-z} . Our goal is to rewrite this with positive exponents.

Step 1: Apply the negative exponent rule. For any non-zero base yy, yn=1yny^{-n} = \frac{1}{y^n}. Hence, (axb)z=1(axb)z (\frac{ax}{b})^{-z} = \frac{1}{(\frac{ax}{b})^z} .

Step 2: Rewrite the expression using the property of exponents for fractions. For (mn)p=mpnp\left(\frac{m}{n}\right)^p = \frac{m^p}{n^p}, we get 1(axb)z=1(ax)zbz=bz(ax)z\frac{1}{(\frac{ax}{b})^z} = \frac{1}{\frac{(ax)^z}{b^z}} = \frac{b^z}{(ax)^z}.

Step 3: Express the power on axax. The expression (ax)z(ax)^z becomes azxza^z \cdot x^z.

Step 4: Substitute back into the expression. We have bzazxz\frac{b^z}{a^z \cdot x^z} which is bzazxzb^z \cdot a^{-z} \cdot x^{-z}.

Therefore, the expression (axb)z (\frac{ax}{b})^{-z} simplifies to bzazxz b^z a^{-z} x^{-z} .

Upon comparing this result with the provided answer choices, we see that it matches the option labeled as choice 2: bzazxz b^z a^{-z} x^{-z} .

Therefore, the solution to the problem is bzazxz b^z a^{-z} x^{-z} .

3

Final Answer

bzazxz b^za^{-z}x^{-z}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Negative exponent means reciprocal with positive exponent
  • Technique: (axb)z=1(axb)z=bzazxz (\frac{ax}{b})^{-z} = \frac{1}{(\frac{ax}{b})^z} = \frac{b^z}{a^z x^z}
  • Check: Multiply original by answer to get 1, confirming reciprocal relationship ✓

Common Mistakes

Avoid these frequent errors
  • Applying negative sign to coefficients
    Don't think negative exponent means changing signs of variables like ax to -ax! The negative exponent only affects the position (reciprocal), not the signs of terms. Always flip the entire expression, keeping all signs unchanged.

Practice Quiz

Test your knowledge with interactive questions

\( (2^3)^6 = \)

FAQ

Everything you need to know about this question

Why doesn't the negative exponent make the variables negative?

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The negative exponent only tells us to take the reciprocal - it doesn't change signs! Think of it as flipping the fraction, not making things negative.

How do I handle multiple variables in the base?

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Apply the exponent to each factor separately. So (ax)z=azxz (ax)^z = a^z \cdot x^z , treating each variable and coefficient independently.

What's the difference between the answer choices?

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Choice 1 incorrectly adds negative signs. Choice 3 stops at fraction form. Choice 4 confuses negative exponents with multiplication. Only choice 2 correctly shows bzazxz b^z a^{-z} x^{-z} .

Can I leave my answer as a fraction instead?

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Yes! bzazxz \frac{b^z}{a^z x^z} and bzazxz b^z a^{-z} x^{-z} are equivalent. However, the form with negative exponents is often preferred as it shows the reciprocal relationship more clearly.

How do I verify this is correct?

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Multiply your answer by the original base: (axb)bzazxz (\frac{ax}{b}) \cdot b^z a^{-z} x^{-z} . If it simplifies to 1, your reciprocal is correct!

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