1) x² + 2x - 8 = (x² + 2x + 1) - 9 = (x + 1)² - 3² = (x + 1 - 3)(x + 1 + 3) =
= (x - 2)(x + 4)
2) x² - 6x + 5 = (x² - 6x + 9) - 4 = (x - 3)² - 2² = (x - 3 - 2)(x - 3 + 2) =
= (x - 5)(x - 1)
3) x² + 12x + 11 = (x² + 12x + 36) - 25 = (x + 6)² - 5² = (x + 6 - 5)(x + 6 + 5) =
= (x + 1)(x + 11)
4) x² - 4x - 5 = (x² - 4x + 4 ) - 9 =(x - 2)² - 3² = (x - 2 - 3)(x - 2 + 3) =
= (x - 5)(x + 1)
3х - 1/4 = 4y - 1/3
5x = 8y + 3
Решение
3х - 4y = 1/4 - 1/3
3x - 4y = 3/12 - 4/12
3x - 4y = - 1/12
12( 3x - 4y ) = - 1
36x - 48y = - 1
48y = 36x + 1
8y = 5x - 3
48y = 30x - 18
36x + 1 = 30x - 18
6x = - 19
X = - 19/6 = - 3 ( 1/6 )
8y = 5•( - 19/6 ) - 3 = - ( 95/6 ) - 3 = - 15 ( 5/6 ) - 3 = - 18 ( 5/6 )
y = - 18 ( 5/6 ) : 8 = - ( 113/6 ) : 8 = - 113/48 = - 2 ( 17/48 )
Ответ ( - 3 ( 1/6 ) ; - 2 ( 17/48 ))