X^2+5x-36<0
x^2+9x-4x-36<0
x(x+9)-4(x+9)<0
(9+x)*(x-4)<0
Oтвет: x<-9
x>4
Сделаем замену: пусть (x-3)² = t, тогда:
t² -5t - 14 = 0
D = 25 + 56 = 81 = 9²
t₁ =
t₂ =
1) (x - 3)² = 7
x² - 6x + 9 - 7 = 0
x² - 6x + 2 = 0
D = 36 - 8 = 28 = 2√7
x₁ = 3 + √7
x₂ = 3 - √7
2) (x - 3)² = -2
x² - 6x + 9 + 2 = 0
x² - 6x + 11 = 0
D = 36 - 44 = ∅
6х+2<5;6х+2-5<0;6х<-3 x<-0,5=1-oe 2-ое х+4-5<0 x<1
<span>Найдите четыре первые члена последовательности (an)
1)an=5-n
а</span>₁ = 5 - 1= 4; а₂ = 5 - 2 = 3; а₃ - 5 - 3 = 2; а₄= 5 - 4 = 1.<span>
2)an= (n^2 +1)/n
а</span>₁ = (1 +1)/2 = 2;
а₂ = (2²+1)/2 =5/2 = 2,5;
а₃ = (3² +1)/3 = 10/3;
.а₄= (4² +1)/4= 17/4