sen(2pi/7)
7/4 x+3/25=9/8 x-12/5
7/4 x+3/25=9/8 x-12/6
7/4 x+2/25=9/8 x-12/5
7/4 x+2/25=9/8 x-12/6
7/4x+2/25=9/8-12/6
7x-2y=10
12y-2x-7z=-6
13z-7y=3
(n-2) x 180 - (n-2) x 180/n = 1296
1313/5915
y'' + (c/x^6 +b/x^2 + a)y =0
