Question 193·Easy·Equivalent Expressions
Which expression is equivalent to , where , , and are positive?
For products of powers, immediately group like bases and apply the product rule: when multiplying with the same base, add the exponents. Work base by base—combine all the exponents, then all the exponents, then all the exponents—being careful with negative exponents as adding signed integers. Only after simplifying fully should you look at the answer choices and match your result, which helps you avoid being distracted by tempting but incorrect exponent combinations.
Hints
Focus on one variable at a time
Ignore the answer choices for a moment. Rewrite the product so that all terms are together, all terms are together, and all terms are together.
Recall the exponent rule for multiplication
When you multiply powers with the same base, do you add, subtract, or multiply the exponents? Apply that rule to the terms, then to the terms, then to the terms.
Handle the negative exponents carefully
When you add a positive and a negative exponent, think of it like adding positive and negative integers. Pay special attention to the terms: one has exponent and the other has exponent .
Desmos Guide
Assign test values to the variables
In Desmos, pick simple positive values for the variables, for example type a=2, b=3, and c=5. (Any positive values work, but small integers are easiest.)
Evaluate the original expression numerically
Type the original expression (a^2*b^-3*c)*(a^-1*b^5*c^-2) and note the numerical result that Desmos gives.
Evaluate each answer choice and compare
One by one, type each answer choice using the same a, b, and c values (for example a*b^2*c^-1, a^3*b^2*c, etc.). The choice whose value matches the value of the original expression is the equivalent expression.
Step-by-step Explanation
Group like bases together
Start by rewriting the product so that the same bases are next to each other:
Now you can combine the exponents for each base separately.
Use the product rule for exponents
Recall: when you multiply with the same base, you add the exponents.
- For :
. - For :
. - For :
.
So the expression becomes a product of these three simplified factors.
Write the final simplified expression and match the choice
Putting the simplified pieces together:
Compare this with the answer choices to see it matches choice A) .