SAT Equivalent Expressions study notes

Equivalent expressions give the same output for every allowed value of x. You can expand, factor, or test a few values to rule out choices, but a few matching values are not a proof. Watch negative signs and squared binomials; that is where plausible wrong answers often come from.

Worked example

Expand 4 − 2(3x − 5)² + x.

First square the binomial: 9x² − 30x + 25. Multiply every term by −2, then combine 4 and x. The result is −18x² + 61x − 46.

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