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.