3)
(100x²⁰-20x¹⁷-6x)-(14x-20x¹⁷+100x²⁰) < 5
100x²⁰-20x¹⁷-6x-14x+20x¹⁷-100x²⁰ < 5
- 20x <5 </p>
-20x: (-20) > 5 : (-20)
x > - 0,25
Ответ: при x>0,25 или при х∈(0,25; +∞)
4)
(а³-1)(а³+2)+(а³+1)(а³-2) =
= a⁶+2a³-a³-2 + a⁶-2a³+a³-2 = 2a⁶-4
Ответ: 2a⁶-4
5)
а)
(7-6с)(6с+7)-9с(2-4с)-49 = 7²-(6с)² - 18с+36с² - 49 =
= 49-36с² - 18с+36с² - 49 = -18с
б)
64b⁶-(8b³-7)(8b³+7)-50 = 64b⁶- ((8b³)²-7²) - 50 =
= 64b⁶- (64b⁶-49) - 50 = 64b⁶- 64b⁶ + 49 - 50 = - 1