For what value of x, the statement [(x/21) × (x/189)] = 1 is correct?

If x³ = (9³ × 6³) / 8, x > 0, then what is the value of x?

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

If a - b = 4 and ab = 12, what is the value of a² + b²?

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

If (3a +6b +c +2d) x (3a - 6b - c +2d) = (3a - 6b +c- 2d) x (3a +6b - c- 2d), then which one of the following is correct ?