(i) x+7+4(x–5) = x+7+4x-20=x+4x+7-20 = 5x-13 = 5×2-13 = 10-13 = -3 [putting x = 2]
(ii) 3(x+2)+5x–7 = 3x+6+5x-7 = 3x+5x+6-7 = 8x-1 = 8×2-1 = 16-1 = 15 [putting x = -1]
(iii) 6x+5(x–2) = 6x+5x-10 = 11x-10 = 11×2-10 = 22-10 = 12 [putting x = -1]
(iv) 4(2x–1)+3x+11 = 8x-4+3x+11 = 8x+3x-4+11 = 11x+7 = 11×2+7 = 22+7 = 29 [putting x = -1]
The bulb in the circuit shown in Fig. does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.