(х-1)(х-7)(х-4)(х+2)=40
(х-1)(х-4)(х-7)(х+2)=40
(x² -4x -x + 4)(x² + 2x - 7x - 14) = 40
(x² -5x + 4)(x² - 5x - 14) = 40
x² - 5x - 5 = t замена
(t + 9)(t - 9) = 40
t² - 81 = 40
t² = 121
t = +- 11
обратно
1. t = 11
x² - 5x - 5 = 11
x² - 5x - 16 = 0
D = b² - 4ac = 25 + 64 = 89
x12 = (5 +- √89)/2
2. x = -11
x² - 5x - 5 = -11
x² - 5x + 6 = 0
D = b² - 4ac = 25 - 24 = 1
x34 = (5 +- 1)/2 = 3 2
ответ x = {2,3,(5 + √89)/2,(5 - √89)/2}
лайкуй и ставь корону
(х-1)(х-7)(х-4)(х+2)=40
(х-1)(х-4)(х-7)(х+2)=40
(x² -4x -x + 4)(x² + 2x - 7x - 14) = 40
(x² -5x + 4)(x² - 5x - 14) = 40
x² - 5x - 5 = t замена
(t + 9)(t - 9) = 40
t² - 81 = 40
t² = 121
t = +- 11
обратно
1. t = 11
x² - 5x - 5 = 11
x² - 5x - 16 = 0
D = b² - 4ac = 25 + 64 = 89
x12 = (5 +- √89)/2
2. x = -11
x² - 5x - 5 = -11
x² - 5x + 6 = 0
D = b² - 4ac = 25 - 24 = 1
x34 = (5 +- 1)/2 = 3 2
ответ x = {2,3,(5 + √89)/2,(5 - √89)/2}
лайкуй и ставь корону