MCQ
The rationalisation factor of $\frac{1}{2\sqrt{3}-\sqrt{5}}$ is:
- A$(\sqrt{3}+\sqrt{5})$
- B$\sqrt{12}+\sqrt{5}$
- C$\sqrt{5}-2\sqrt{3}$
- D$\sqrt{3}+2\sqrt{5}$
✓
Answer
- $\sqrt{12}+\sqrt{5}$
Solution:
$\frac{1}{2\sqrt{3}-\sqrt{5}}$
$=(2\sqrt{3}-\sqrt{5})(2\sqrt{3}+\sqrt{5})$
$=12-5$
$=7$
Rational number
$(2\sqrt{3}+\sqrt{5})=(\sqrt{4\times3}+\sqrt{5})=\sqrt{12}+\sqrt{5}$
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