Question 34·Easy·Equivalent Expressions
Which expression is equivalent to ?
For expression-equivalence questions, first remove parentheses by distributing carefully—especially when there is a minus sign in front of a parenthesis, which changes both signs inside. Then group like terms (all -terms together, all constant terms together) and simplify step by step. To avoid sign mistakes under time pressure, write intermediate steps clearly instead of trying to do everything in your head.
Hints
First focus on distributing
Start by expanding and also think about what happens when you have a minus sign in front of the parentheses in .
Be careful with the minus in front of
Treat as times . What does that do to both and ?
Combine like terms at the end
Once the parentheses are removed, group the -terms together and the constant numbers together, then simplify each group.
Desmos Guide
Enter the original expression
In the first line, type y = 3(2x - 5) - (4x - 7) + 6 to represent the original expression as a function.
Enter each answer choice as a separate function
On new lines, type y = 2x - 2, y = 2x + 2, y = -2x - 2, and y = -2x + 2. Each line will create a different graph.
Compare the graphs or use a table
Use the table feature (click the gear next to an equation and choose "Convert to table") or visually compare the graphs. The correct choice will have a graph that lies exactly on top of the graph of the original expression and will give the same -values as the original for every you test.
Step-by-step Explanation
Distribute within each set of parentheses
Start by expanding the parentheses.
-
For , distribute :
- So .
-
For , think of distributing :
- So .
Now rewrite the whole expression using these results:
Group like terms
Group the terms with together and the constant terms together:
- -terms:
- Constant terms:
Compute each group separately:
- For the constants:
Write the final simplified expression and match the choice
Combine the simplified -term and constant term:
- The expression becomes .
Now look at the answer choices and select the one that matches . That is choice A.) .