Question

Find conjugate of:
$3-\sqrt{5}$

• A. $3+\sqrt{5}$
• B. $3-\sqrt{5}$
• C. $3\sqrt{5}$
• D. None of these

Answer 1

The correct option is A $3+\sqrt{5}$

$3-\sqrt{5}$
The procedure of multiplying a surd by another surd to get a rational number is called Rationalization. The operands are called rationalizing factor (RF) of the other
$(3-\sqrt{5})\times (3+\sqrt{5})=3^2-(\sqrt{5}{)}^2=9-5=4$
The Rationalizing factor of $3-\sqrt{5}$ is $3+\sqrt{5}$