Question

if 'a' and 'b'are rational numbers and 2+5root7/2--5root7a+root7b

Answer 1

2 + 5√7)/(2 – 5√7)
= [(2 + 5√7)/(2 – 5√7)] × [(2 + 5√7)/(2 + 5√7)]
= [ (4 + 175 + 20√7)/(4 – 175)]
= [(179 + 20√7)/(-171)]
= a + b√7
So, a = - 179/171
b = - 20/171