Question 73·Easy·Equivalent Expressions
Which expression is equivalent to , where , , and are nonzero?
For exponent simplification problems, immediately separate the expression by base (all terms together, all terms together, etc.) and apply the rule to each base. Add the exponents carefully, paying close attention to negative signs, and do the arithmetic for each variable one at a time before matching your simplified result to the answer choices. This minimizes mistakes and speeds up your work on SAT exponent questions.
Hints
Group like bases
Rewrite the expression by grouping the factors with the same base: put the terms together, the terms together, and the terms together.
Remember the rule for multiplying exponents
When you multiply expressions like and with the same base , think about what happens to the exponents. Do you add, subtract, multiply, or divide them?
Be careful with negative exponents
When you add exponents that include negative numbers (like and ), treat it as normal integer addition. Write out the sums for the exponents of , , and separately.
Check each variable one by one
After you find the combined exponent for each variable, compare those exponents with the ones in each answer choice to see which matches.
Desmos Guide
Assign numerical values to the variables
In Desmos, choose nonzero values that are not or (to avoid accidental matches). For example, type:
a = 2b = 3c = 5
Evaluate the original expression
On a new line, type the original expression using these values:
(a^-2 * b^6 * c^3) * (a^5 * b^-2 * c^-1)
Note the numerical value that Desmos gives for this line.
Test each answer choice against the original expression
On separate lines, enter each answer choice using the same , , and values, for example:
a^-7 * b^4 * c^4a^3 * b^4 * c^2a^3 * b^8 * c^2a^7 * b^4 * c^4
Compare the numerical result of each with the value from the original expression. The choice whose value matches exactly is the equivalent expression.
Step-by-step Explanation
Recall the exponent rule for multiplying same bases
When you multiply powers with the same base, you add the exponents:
We will use this rule separately for , , and .
Combine the terms
Look at the factors:
- From the first parentheses:
- From the second parentheses:
Multiply them using the rule:
So the combined part is .
Combine the terms
Now look at the factors:
- From the first parentheses:
- From the second parentheses:
Multiply them:
So the combined part is .
Combine the terms and write the final expression
Finally, look at the factors:
- From the first parentheses:
- From the second parentheses:
Multiply them:
Putting all three variables together, the product is
This matches answer choice B.