6. \( A=5 a^{2}-2 a b-3 b^{2}, B=3 a^{2}+2 a b+b^{2} \) olarsa, \( A-(B-2 A-(2 B-2 A))- \) nitapin. \( \begin{array}{llll}\text { A) } 2 a^{2}-4 a b & \text { B) } 8 a^{2}-2 b^{2} & \text { C) } 8 a^{2}-4 b^{2} & \text { D) } 2 a^{2}-4 b^{2}\end{array} \)

(a) \( \frac{2 x-3}{4}=5 \)

Решите уравнение \( \frac{x^{2}-9 x+25}{2 x^{2}-3 x-5}+\frac{5}{x+1}=1 \)

ection-A consists of 20 questions of 1 mark each. The equation which has no real roots is \( \begin{array}{llll}\text { (a) } 3 x^{2}=8 x-2 & \text { (b) } x^{2}-11 x=16 & \text { (c) } 7 x^{2}-1=-8 x & \text { (d) } 2 x^{2}+5 x+6=0\end{array} \)

The ring \( \mathbb{Z} \) has no nontrivial idempotent elements, whereas \( \mathbb{Z} \times \mathbb{Z} \) has the idernpotent elements \( (1,0) \) and \( (0,1) \).

Describe the steps involved in finding the inverse of a function algebraically.