Question 122·Medium·Equivalent Expressions
Which expression is equivalent to ?
For products like a binomial times a trinomial, systematically use the distributive property: multiply each term in the binomial by each term in the trinomial, then carefully combine like terms. If you notice a special pattern such as , you can also use the shortcut to jump directly to the simplified form, but always double-check signs and coefficients.
Hints
Think about how to multiply a binomial and a trinomial
You can use the distributive property: multiply each term in by each term in .
Write out all partial products
First compute , , and . Then compute , , and .
Combine like terms carefully
After you write all six terms, group the terms, the terms, the terms, and the constants. Notice which ones cancel out when you add them.
Desmos Guide
Enter the original expression
Type y1 = (2x - 3)(4x^2 + 6x + 9) to represent the given product.
Test each answer choice
For each option, type it as a new function, for example y2 = 8x^3 + 27, y3 = 4x^3 - 27, etc. Compare each graph to : the correct expression will have a graph that lies exactly on top of for all visible values.
Verify numerically if you prefer
You can also create a table for and one answer choice (tap the gear next to the function and select 'table') and compare the -values at several -values (like ). The equivalent expression will match at every tested .
Step-by-step Explanation
Distribute each term in the binomial
Use the distributive property to multiply by each term in :
Now distribute inside each part:
So the full expanded expression is:
Combine like terms to simplify
Group and combine like terms:
- terms:
- terms:
- terms:
- Constant term:
So the simplified expression is:
Therefore, the equivalent expression is .