2x-y+15y=12⇒2x+14y=12
12-4x-3y=60⇒-4x-3y=48
домножим 1 ур-е на 2
4х+28у=24
прибавим ко 2
25у=72
у=72/25=2,88
2х+14*2,88=12
2х=12-40,32=-28,32
х=-14,16
<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>
7+36х-27=88
36х=88+27-7
36х=108
х=3
2sinxcosx+2cos^2x-2sin^2x-cos^2x-sin^2x=0
2sinx*cosx+cos^2x-3sin^2x=0
-3tg^2x+2tgx+1=0
D=4+4*3*1=16
t=(-2+4)/-6=-1/3
t=(-2-4)/-6=1
tgx=(-1/3) tgx=1
x=-arctg1/3+pik x=pi/4+pin
(a^2 - 8a + 16) - 10a^2 + 8a.
a^2 - 8a + 16 - 10a^2 + 8a = -9a^2 + 16
Если а= -1/3, то -9*(-1/3)^2 + 16 = 25