20. A video game store allows customers to rent games for \( \$ 4.75 \) each. Customers can also buy a membership for \( \$ 54 \) annually, and video games would only cost \( \$ 2.50 \) each. Write and solve an equation to find the number of video games a customer would have to rent in a year in order for the two options to be equal.

If \( x-6=0 \) is one of the solutions df the equation \( x+\frac{40}{x}=16 \), determine ONE value of \( y \) for which \( 2 y+3+\frac{40}{2 y+3}=16 \)

12.3 The equations \( x^{2}+a x+b=0 \) and \( x^{2}+b x+a=0 \) both have real and equal roots. Solve for \( a \) and \( b \), where \( a>0 \) and \( b>0 \).

24 Expresa com a identitats notables. \( \begin{array}{ll}\text { a) } 49 x^{2}-16 & \text { b) } 36 x^{2}-1 \\ \text { c) } x^{2}-18 x+81 & \text { d) } 121-100 x^{2} \\ \text { e) } 9 x^{2}+12 x+4 & \text { f) } 9 x^{2}-24 x+16 \\ \text { g) } 25-100 y^{2} & \text { h) } 4 x^{2}+16 x+16\end{array} \)

a) \( \left(-2 x^{2}\right)\left(x^{2}-2 x+3\right) \frac{1}{2} \)

If \( x-6=0 \) is one of the solutions of the equation \( x+\frac{40}{x}=16 \), determine ONE value of \( y \) for which \( 2 y+3+\frac{40}{2 y+3}=16 \)