1 + root 2 + root 1 / 3 1 + root 2 + root 3 + root 3 + root 4 +... + root 2008 + root 2009 + root 2009 + root 2010 =?

1 + root 2 + root 1 / 3 1 + root 2 + root 3 + root 3 + root 4 +... + root 2008 + root 2009 + root 2009 + root 2010 =?

1 + root 2 + root 3 + root 3 + root 4 +... + root 2008 + root 2009 + root 2009 + root 2010 = root 2-1 + root 3-root 2 + root 4-root 3 + +Root 2009 root 2008 + root 2010 root 2009 = root 2010-1

Evaluate sin115 ° sin70 ° - sin25 ° sin20 °
Don't come until you're done

sin115°sin70°-sin25°sin20°
=sin70°sin65°-sin20°sin25°
=cos20°cos25°-sin20°sin25°
=cos(20°+25°)
=cos45°
=Root 2 / 2

C(10,r+1)+C(10,17-r)=
46 or 20

The value of R is conditional. As a permutation number, the superscript must be less than or equal to the subscript
r+1

I figured out 18
A TV station continuously broadcast five advertisements, including three different commercial advertisements and two different Olympic advertisements. It is required that the last advertisement to be broadcast must be Olympic advertisements, and if two Olympic advertisements cannot be broadcast continuously, how many different broadcast modes are there
The last one is fixed, because it must be the Olympic Games. The penultimate one is not allowed to be the Olympic Games. Only the first three can be the Olympic Games, and the remaining three are in full platoon

36 kinds of requirements: the last one to be broadcast must be Olympic advertising, and two Olympic advertising cannot be broadcast continuously, that is to say, the last two must be a commercial plus an Olympic advertising, which has 3 * 2 = 6 kinds; the remaining three kinds of advertising are the arrangement and combination of two commercial and an Olympic, one has 3 * 2 * 1 = 6 kinds; so combined with