If the points (1, x), (5, 2) and (9, 5) are collinear, the value of x is:

If x + (1/y) = 1 and y + (1/z) = 1, then the value of z + (1/x) is

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

If (a² − 1)/a = 2, then the value of (a⁶ − 1)/a³ is:

If 2^(x−1) + 2^(x+1) = 1280, then the value of x²+9x is

If x + (1/x) = 3, then the value of x³ + (1/x³) is :