Make r subject of the formula given that \(\frac{x}{r+a}=\frac{a}{r}\)

The inverse function f(x) = 3x + 4 is

If -2 is the solution of the equation 2x + 1 - 3c = 2c + 3x - 7, find the value of c.

The binary operation * is defined on the set of integers p and q by p*q = pq + p + q. Find 2 * (3 * 4).

The sum to infinity of the series: 1 + (1/3) + (1/9) + (1/27) + ... is