How to answer it
- Expand any squared or multiplied parentheses.
- Combine like terms.
- Compare with the choices, or test with x = 1 if you’re unsure.
Worked example
An original question in the SAT format, already answered.
SAT MathWorked example
(x + 4)² − 16
Which expression is equivalent to the expression shown?
- Ax²
- Bx² + 16
- Cx² − 8x
- Dx² + 8x
Answer: D. (x + 4)² = x² + 8x + 16, and subtracting 16 leaves x² + 8x. Check with x = 1: (5)² − 16 = 9, and 1 + 8 = 9.
The most common trap
Squaring each term separately. (x + 4)² is not x² + 16; you need the middle term 8x.
Practice it
Hourly Prep’s daily sets mix equivalent expressions with the rest of SAT Math, and send more of it your way when it’s a weak spot. See how the SAT prep plan works, or browse the other SAT skill guides.
For pacing and strategy across the whole section, read our guide to Desmos on the SAT. To fit this skill into a schedule, see the SAT study plan guide.