Question

if a²+ 1/a²=18 find (a-1/a) and (a+1/a)

Answer 1

$(x - \frac{1}{x} ) {}^{2} = x {}^{2} + \frac{1}{x} {}^{2} - 2 \times x \times \frac{1}{x} = 18 - 2 =16$
hence answer will be 4