Find the discriminant of the following quadratic equation: $9x^{2} - bx + 3 = 0$.

Solve the quadratic equation $25 x^{2}-30 x+3=0$ by using the method of completing the square.

Find the roots of the following quadratic equation by using the quadratic formula,if they exist: $(x+4)(x+5)=3(x+1)(x+2)+2x$

Solve the following equation using the method of factorization: $x + 3 + \frac{2}{x} = 0$.

State whether the following statements are true or false. Justify your answers.
$(i)$ Every quadratic equation has at most two roots.
$(ii)$ If the coefficient of $x^{2}$ and the constant term of a quadratic equation have opposite signs,then the quadratic equation has real roots.

Who gave the general formula to solve quadratic equations?