f(x)=cos²(x/4)-sin²(x/4)=cos(2*(x/4))=cos(x/2)
f'(x)=-sin(x/2)*(1/2)=-sin(x/2)/2=0
-sin(x/2)/2=0 |×(-2)
sin(x/2)=0
x/2=πn |×2
x=2πn.
<span>х(х-2)-(х+1)(х+3)=4
x^2-2x-(x^2+3x+x+3)=4
</span>x^2-2x-(x^2+4x+3)=4
x^2-2x-x^2-4x-3=4
-6x-3=4
-6x=4+3
-6x=7
x=-7/6 (x=-1*1/6)
1) (-2)^умн m^2 умн 3m умн n^4 умн m^5= -48 m^8 n^5
2)-7a^3b+4a^3b-8a^3b=- 11 a^3b
3)3a^2 умн 5ab^2 + 2a^3 умн 10b умн b= 15 a^3b + 20 a^3 b^2 =35 a^3b^2