Question

Find the product of following with its conjugate pair.

$\sqrt{5}+1$

• A. conjugate pair $=\sqrt{5}+1$, product $3$
• B. conjugate pair $=\sqrt{5}-1$, product $4$
• C. conjugate pair $=\sqrt{5}+1$, product $4$
• D. conjugate pair $=\sqrt{5}-1$, product $3$

Answer 1

The correct option is B conjugate pair $=\sqrt{5}-1$, product $4$

The conjugate of $\sqrt{5}+1$ is $\sqrt{5}-1$
Product = $(\sqrt{5}+1)\times (\sqrt{5}-1)={\sqrt{5}}^2-1^2=5-1=4$