SAT · Additional Topics in Math · Complex numbers
Question sat-q-00211
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The question
If 4x + 8 = 0, what is the value of x?
- -2
- -3
- 2
- -1
Show answer & worked solution
Answer: -2
Worked solution. Subtract 8 from both sides: 4x = -8. Divide both sides by 4: x = -2.
Why each wrong choice is wrong. The off-by-one and negated answers are common arithmetic-slip distractors. Watch the sign of the constant term when you move it across the equals sign.
Test-day tactic. When the stem is short, do the algebra straight rather than plugging in answer choices — it's faster.
About this question type
A small number of items test complex-number arithmetic. The key fact is i² = −1; multiplication is just FOIL with that substitution. Division by a complex number requires multiplying by the conjugate.
You will see a question shaped like this one on roughly every other official SAT form, typically at an early position in the section, where missing them carries an outsize penalty because the curve assumes everyone in your band gets them right. Treat any miss in this subtopic as a signal to drill the subtopic page before you do another full practice test.