In an equivalent expression question, the correct choice must have the same value as the original for every value of the variable. When both terms share a factor, pull out the greatest common factor by dividing each term. Desmos can check a value, but one matching value alone doesn't prove the expressions are equivalent.
Hints
- Hint 1
A common factor divides every term. Look at both and : what is the largest number they share, and what power of appears in both?
- Hint 2
Factoring runs multiplication backward. After finding the shared factor, divide each term by it to find what belongs inside the parentheses.
Step-by-step
Factor out the shared term
Step 1Find what both terms share
Both and contain : divides both coefficients, and each term has at least one . So is the greatest common factor. Divide each term by that factor to find what stays inside the parentheses:
- Step 2
Get a value to check
Choose the nonzero value so a missing factor of won't disappear. Type , then in Desmos. It gives for the original expression.
- Step 3
Build the product and check it
Put the shared outside and the quotients and inside: . Type on the next Desmos line; it also gives . That value checks the arithmetic, while factoring proves the match for every . So is the equivalent expression. Choice D.