Question

please answer anyone one question from these ​

Answer 1

$\frac{\sqrt{7}-1 }{\sqrt{7}+1 } - \frac{\sqrt{7}+1 }{\sqrt{7}-1 } = a + b \sqrt{7} \\\\\frac{\sqrt{7}-1 }{\sqrt{7}+1 } * \frac{\sqrt{7}+1 }{\sqrt{7}-1 } - \frac{\sqrt{7}+1 }{\sqrt{7}-1 } * \frac{\sqrt{7}-1 }{\sqrt{7}+1 } = a + b \sqrt{7}\\\\factorize\ by\ algebraic\ identities = a^2-b^2 = (a+b)(a-b)\\\\\frac{7-1}{7-1} - \frac{7-1}{7-1} = a + b \sqrt{7} \\\\\frac{6}{6} - \frac{6}{6} = a + b \sqrt{7} \\\\1 - 1 = a + b \sqrt{7} \\\\0 = a + b \sqrt{7}$

therefore both a and b are 0

$hope \ it \ helps \ !!$