q=b4/b3=-3/6=-1/2
b3=b1*q^2=6
b1*(-1/2)^2=6
b1=24
S=b1/(1-q)=24/(1+1/2)=24/1,5=16
X∈R, D(y)=R
-1≤sinx≤1
10≤sinx+11≤12
E(y)∈[10;12]
2cos²x=1+4sin4x
2(1+cos2x/2)=1+8sin2xcos2x
1+cos2x=1+8sin2xcos2x
1+cos2x-1+8sin2xcos2x=0
cos2x+8sin2xcos2x=0
cos2x(1+8sin2x)=0
cos2x=0
2x= π/2+πk |:2
x= π/4+πk/2
sin2x=-1/8
2x=(-1)^k+1 arcsin1/8+πn |:2
x=(-1)^k+1 arcsin1/16+πn/2
-sqrt(75)=-sqrt(25*3)=-5sqrt(3)
0,1sqrt(128)=0,1sqrt(64*2)=0,8sqrt(2)
0,4sqrt(40)=0,8sqrt(10)
sqrt(12x^2)=2xsqrt(3)
sqrt(18y^2)=-3ysqrt(2)
sqrt((5a)^4)=25a^2