If 1² + 2² + 3² + ... + 10² = 385, then 3² + 6² + 9² + ... + 30² is equal to:

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

√(2.25) + √(0.0064) + √(2.89) + 1 is equal to:

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

If 2^(2x−1) + 4^x = 2^(x−1/2) + 2^(x+1/2), then the ratio (1−x)/(1+x) is

If 5^x = 1/3, then 5^−7x = ?