Найдите несколько чисел, кратных двум данным числам. Укажите най- меньшее общее кратное этих чисел: а) 3 и 7; 6) 4 1 5; в) би 12; г) 4 и 6. Найдите несколько общих знаменателей дробей, назовите их наимень

Х⁴ - 3х³ - 2х² - 6х - 8 = 0

Прибавим и отнимем 2х² в левой части уравнения:
х⁴ - 3х³ - 2х² + (- 2х² + 2х²) - 6х - 8 = 0

х⁴ - 3х³ - 4х² + 2х²)- 6х - 8 = 0

х²(х² - 3х - 4) + 2х² - 6х - 8 = 0

х²(х² - 3х - 4) + 2(х² - 3х - 4) = 0

(х² - 3х - 4)(х² + 2) = 0

1) х² + 2 = 0
х² = -2 - это невозможно
Так как х² > 0 или х² = 0
х² + 2 ≠ 0

2) х² - 3х - 4 = 0
D = 3² + 4•4 = 9 + 16 = 25
√D = √25 = 5
х1 = (3+5)/2 = 8/2 = 4
х2 = (3-5)/2 = -2/2 = -1

ответ: 4; -1.

Проверка
При х = 4
4⁴ - 3•4³ - 2•4² - 6•4 - 8 =
= 256 - 192 - 32 - 24 - 8 = 0

При х = -1
(-1)⁴ - 3•(-1)³ - 2•(-1)² - 6•(-1) - 8 =
= 1 + 3 - 2 + 6 - 8 = 0

1. 2х7 = 14 х 50 = 700 х 9 = 6 300

 

2.    6200            3. 25 х 72 = 1800 х 4 = 7200 х 40 = 288 000        4.   1645

    + 1730                                                                                               +2316

                                                                                               

       7930                                                                                                 3961

    +   800                                                                                               +1355

                                                                                              

       8730                                                                                                  5316

     +  170                                                                                               +   684

                                                                                               

       8900                                                                                                  6000