Question

Find conjugate of:
3$\sqrt{2}$ -1

• A. 3$\sqrt{2}$ +1
• B. 3$\sqrt{2}$ -1
• C. 3$\sqrt{2}$
• D. None of these

Answer 1

The correct option is A 3$\sqrt{2}$ +1

$3\sqrt{2}+1$
The procedure of multiplying a surd by another surd to get a rational number is called Rationalisation
The operands are called rationalizing factor (RF) of the other
$(3\sqrt{2}+1)\times (3\sqrt{2}-1)=(3\sqrt{2}{)}^2-1^2=18-1=17$
The Rationalizing factor of $3\sqrt{2}+1$ is $3\sqrt{2}-1$