A1 + d(n-1) = an
a9 = a1 + 8d = 11,5
a24 = a1 + 23d = -22
Решаем систему, вычитая из второго уравнения первое, получаем
23d - 8d = -22 - 11,5
15d = -33,5
d = -33,5/15
<span>|x^2-5x|-6>0
</span><span>|x^2-5x|>6</span>⇒
<span>[x</span>²-5x<-6 (1)
<span>[x</span>²-5x>6 (2)
<span>1)x</span>²-5x+6<0
<span>D=25-24=1>1
x1+x2=5 U x1*x2=6
x1=2 x2=3
+ _ +
-----------------(2)---------------------(3)------------------
2<x<3
2)x</span>²-5x-6>0
<span>D=25+24=49>0
x1+x2=5 U x1*x2=-6
x1=-1 x2=6
+ _ +
--------------(-1)------------------(6)--------------
x<-1 U x>6
Ответ x</span>∈(-∞;-1) U (2;3) U (6;∞)<span>
</span>
(a+1)(a²-a+1)-a(a+1)≥0
(a+1)(a²-a+1-a)≥0
(a+1)(a²-2a+1)≥0
(a+1)(a-1)²≥0
a=-1 a=1
_ + +
---------------------------------------------------
-1 1
a∈[-1;∞)
2x^2 + 3x + 4 = 0
D = 9 - 4*2*4 = 9 - 32 = - 23< 0
нет решений