GCE Mathematics 2024 Objective — Question 6
Question 6 of 50 from the General Certificate of Education (GCE) Mathematics 2024 Objective paper, with the correct answer and a full explanation.
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If (3−4√2)(1+3√2)=a+b√2, find the value of b.
- A. A. 5Correct
- B. B. -5
- C. C. -21
- D. D. 21
Explanation
(3−4√2)(1+3√2)=3+9√2−4√2−4(2×3)... expanding: 3+9√2−4√2−12(2)^0.5×... =3+9√2−4√2−24 = −21+5√2 = a+b√2. So a=−21, b=5.
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