If sin A = 5/13, then tan A equals

If x² + 1/x² = 51, then (x − 1/x) is equal to

If 5^x = 1/3, then 5^−7x = ?

If ω (ω ≠ 1) be a cube root of unity and (ω + 1)^8 = a + bω, then a.b equals

If a^b = c^d, then log a / log c is

If x + 1/x = k and x² + 1/x² = k, then values of k are