Question 116·Medium·Equivalent Expressions
For and , which of the following expressions is equivalent to the expression above?
For expressions with radicals and variables, first convert all roots to fractional exponents so everything is in the same language of powers. Simplify the numerator and denominator separately, then use exponent rules (especially ) to combine them, being careful to apply powers to each factor and to keep any numerical constants like . Finally, match your simplified expression to the closest answer choice without re-expanding into radicals unless necessary.
Hints
Turn radicals into exponents
Try rewriting both the numerator and denominator using fractional exponents: as power and fourth root as power .
Simplify the numerator first
For , apply the power separately to , , and . What is ? How do you multiply exponents on and ?
Match the form in numerator and denominator
Rewrite as and then as . After that, you can subtract exponents for and when dividing.
Use the division rule for exponents
Remember: when dividing like bases, use . Apply this separately to and to , and see what is left.
Desmos Guide
Enter the original expression
In Desmos, type the original expression using exponents: (16*p^6*q^2)^(1/4) / sqrt(p*q).
Assign specific positive values to and
On new lines, enter p = 9 and q = 4 (or any other positive values). Desmos will now show a single numerical value for the original expression; note this value.
Compare with each answer choice
On separate lines, enter each option using the same and : p, 2*p, 2*p*q, and 2*sqrt(p). Compare the numerical values to the value from the original expression and see which option matches. You can change and to other positive values to confirm your result stays consistent.
Step-by-step Explanation
Rewrite roots as fractional exponents
Write each radical using exponents.
- The numerator is .
- The denominator is .
So the whole expression becomes
Now you can use exponent rules instead of radical rules.
Simplify the numerator
Apply the power to each factor inside :
- is the fourth root of , which is .
- .
- .
So the numerator becomes
Now the expression is
Rewrite the denominator in terms of and
Rewrite by applying the exponent to each factor:
Now the whole expression is
Both numerator and denominator are now products of powers of and .
Use exponent rules to divide and identify the equivalent choice
When you divide powers with the same base, subtract the exponents:
For :
For :
So
Thus the original expression simplifies to , which matches choice B.