1•(18х+26)=1•(118х-24)
18х+26=118х-24
18х-118х=-24-26
-100х=-50
х=-50:(-100)
х=0,5
1й пожимает 6ти
2й--------------5ти
3й--------------4м
4й--------------3м
5й--------------2м
6й--------------одному
6+5+4+3+2+1=21 рукопожатий
или по формуле n(n-1)/2=7(7-1)/2=21
(cos(5π/2-α)- sin(α-π/2))(sin(π-α)+cos(3π-α))=(cos(2π+π/2-α)+sin(π/2-α))(sin(π-α)+cos(2π+π-α))=(cos(π/2-α)+sin(π/2-α))(sin(π-α)+cos(π-α))=(sinα+cosα)(sinα-cosα)=sin²α-cos²α=-(cos²-sin²α)=-cos2α=-cos(-π/8×2)=-cos(π/4)=-√2/2
Ответ:
Объяснение:
1. -(√2-3)⁴=((√2-3)²)²=-(2-6√2+9)²=-(11-6√2)²=-121+132√2-72=-193+132√2.
2. -193+132√2-144√2=-193-12√2.
3. (√(7-3√5))*(3+√5)= (√(7-3√5))*(√(3+√5)²)= (√(7-3√5))*(√(9+6√5+5))=
= (√(7-3√5))*(√(14+6√5))=√(2*(7-3√5)*(7+3√5))=
=√(2*(49-45))=√(2*4)=2√2
4. 2√2-193-12√2=-193-10√2.