Вправи: 72

72. Спростіть вираз:

1) 6a-116a-8 + 4a-716a-8 + -2a-28-16a = 6a-116a-8 + 4a-716a-8 + -(2a+2)-(16a-8) = 6a-116a-8 + 4a-716a-8 + 2a+216a-8 = 6a-1+4a-7+2a+216a-8 = 12a-616a-8 = 6(2a-1)8(2a-1) = 34;

2) 2a2+ 12aa2- 25 + 8a-925- a2 – a2- 14a-16a2- 25 = 2a2+ 12aa2- 25 – 8a-9a2- 25 – a2+ 14a-16a2- 25 = 2a2+ 12a- 8a-9- (a2+ 14a-16)a2- 25 = 2a2+ 12a-8a+9- a2- 14a+16a2- 25 = a2- 10a+25a2- 25 = (a-5)2a-5(a+5) = a-5a+5.