Question 80·Medium·Equivalent Expressions
Which of the following expressions is equivalent to the expression above?
For rational expressions with exponents, simplify in a fixed order: first handle any powers on parentheses using and , then simplify numerical coefficients, and finally combine exponents for each variable with . Leave negative exponents until the end, then convert them to positive exponents by moving factors between numerator and denominator. Working step by step like this reduces mistakes and makes it easier to match your result with the correct answer choice.
Hints
Handle the power on the parentheses
Focus on the numerator . How do you square the 4, the , and the separately using ?
Simplify step by step
After you simplify the numerator, write the whole fraction with the new numerator over , and then simplify the numerical part before working with the variables.
Use exponent rules when dividing
When you divide powers with the same base, use . Apply this separately to the terms and the terms.
Deal with negative exponents at the end
If you end up with negative exponents, remember you can move the factor to the denominator (or numerator) to make the exponent positive.
Desmos Guide
Enter the original expression
In Desmos, type the original expression exactly (using p and q as variables):
(4*p^(3/2)*q^(-1))^2 / (8*p^(-1/2)*q^3)
This will be your reference expression.
Create sliders for p and q
Add p = 2 and q = 3 (or any nonzero values) as separate lines; Desmos will make sliders. These values will be used to compare the expressions numerically.
Type each answer choice as a separate expression
On new lines, enter each option, for example:
2*p^(7/2)/qp^3/q^2p^4/(2*q^5)2*p^(7/2)/q^5
Desmos will compute a numeric value for each expression using the same and as the original.
Compare values to see which expression matches
Look at the numeric value of the original expression and each answer choice. The correct choice is the one whose value matches the original expression for your chosen and ; you can change the slider values (still nonzero) to confirm they continue to match.
Step-by-step Explanation
Simplify the numerator by squaring
Start with the expression
Square each part inside the parentheses:
- (multiply exponents: )
So the numerator becomes , and the whole expression is
Simplify the numerical coefficients
Now simplify the numbers (coefficients):
So the expression becomes
Combine exponents for and
Use the rule for like bases.
For :
For :
So the expression becomes
Rewrite with positive exponents and match the choice
A negative exponent means the factor belongs in the denominator: .
So
This matches answer choice D, .