Sin pi/7 (+)
cos 7pi/8 (-)
cos6 (+)
3)Решить дробно-рациональное нервенство(x-2)/(x+2)(x-5) ≥ 0 ;
методом интервалов:
- + - +
---------- (-2) ------------ [2] -------------- (5) -------------
x∈ ( -2 ; 2] U (5 ;∞) .
=11,5330078125
..............................
X^2 - 2x - 8 = 0
D = 4 + 4*8 = 32 + 4 = 36 = 6^2
x1 = ( 2 + 6)/2 = 8/2 = 4;
x2 = ( 2 - 6)/2 = - 4/2 = - 2
2) 1.5(X-6)=1.4(X+5)
1.5X-9=1.4X+7
0.1X=16
X=160
1) 0.7X-3.5=X-0.1
0.7X-X=3.5-0.1
-0.3X=3.4
X= -11.333(3)