Question 157·Easy·Equivalent Expressions
Which of the following is equivalent to ?
For equivalent-expression questions, first remove all parentheses by distributing carefully, paying special attention to minus signs in front of parentheses (treat them as multiplying by ). Then combine like terms by grouping terms together and constants together. Work step by step in a clear vertical layout to avoid sign errors, and only match your simplified result to the answer choices at the end.
Hints
First distribute the 4
Ignore the second parentheses for a moment and expand by multiplying 4 with each term inside the parentheses.
Handle the minus sign before the second parentheses
Treat the minus sign in front of as multiplying everything inside by ; how does that change each term?
Combine like terms carefully
After removing all parentheses, put the terms together and the constant numbers together, then simplify each group.
Desmos Guide
Enter the original expression
In one expression line, type 4(2x - 3) - (x - 5) so Desmos graphs or evaluates this as your reference expression.
Enter each answer choice for comparison
On separate lines, type each option: 7x - 7, 7x + 7, 9x - 17, and 9x - 7. You can either compare the graphs or create a table for each expression.
Check for equivalence
Use a table (click the gear icon and add table) for the original expression and each choice, and compare their -values at several -values (for example, ). The correct choice will have the same -value as the original expression for every you test.
Step-by-step Explanation
Distribute the 4 into the first parentheses
Start with the given expression:
Distribute the 4 to both terms inside the first parentheses:
So the expression becomes:
Distribute the negative sign into the second parentheses
Think of the minus sign before as multiplying by .
Distribute to both terms inside the parentheses:
Now rewrite the expression without parentheses:
Group like terms
Group terms together and constant terms together:
- terms:
- Constant terms:
Now simplify each group.
Simplify to find the equivalent expression
Simplify the grouped terms:
So the original expression is equivalent to:
This matches answer choice A) 7x - 7.