Surds Quiz
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5 questions, one answer each
Each answer is checked as you go, with why.
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1. Which of these is a surd?
- A. √16
- B. √25
- C. √7
- D. √100
2. Simplify √45.
- A. 3√5
- B. 5√3
- C. 9√5
- D. 15√3
3. Rationalise 6/√3.
- A. 2√3
- B. 3√3
- C. 6√3
- D. 2√2
4. What is the conjugate of 2 + √5, and why is it used to rationalise a denominator?
- A. 2 − √5, because multiplying by it creates a difference of two squares that removes the surd
- B. √5 − 2, because it reverses the sign of both terms
- C. 2 + √5, because multiplying identical expressions cancels the surd
- D. −2 − √5, because it makes the expression negative
5. Simplify (√3 + 2)(√3 − 2).
- A. 1
- B. -1
- C. 3 − 4√3
- D. 7