3t^2 - 2t - 1 = 0
D = 4 + 12 = 16 ; V D = 4
t1 = ( 2 + 4 ) : 6 = 1
t2 = ( 2 - 4 ) : 6 = - 1/3
Ответ 1 ; - 1/3
(2/(n+1)! - 3/n!) : (5/n!- 4n/(n+1)!)
1) 2/ (n+1)! -3/ n!= 2/(n+1)! - 3(n+1)/(n+1)! = (2-3n-3) / (n+1)!
2) 5/n! - 4n/(n+1)! = (5(n+1) -4n) / (n+1)! = (n+5)/ (n+1)!
3) (-3n-1)/ (n+1)! : ((n+5)/(n+1)!)= (-3n-1)(n+1)! / (n+1)!(5+n) =
= (-3n-1) / (5+n)
ответ при n = 2
1) 180° - 78° = 102°
2)102° ÷ 2 = 51°
Ответ: 51°
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