" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2024 KUDO.TIPS - All rights reserved.
(n-1)n<1/2(n+5)(n+6)
n²-n<1/2(n²+11n+30)
n²-n<1/2n²+11/2n+15
1/2n²-13/2n-15<0/(-2)
-n²+13+30>0
Δ=169+120=289
√Δ=17
n=-13-17/-2=15
n=-13+17/-2=-2
(n-1)n/n²+6n+5n+30 <1/2 /×(n²+6n+5n+30)
n(n-1) < 1/2×(n²+6n+5n+30)
n²-n < 1/2n²+11/2n+15
n²-1/2n²-n-11/2n-15 < 0
1/2n²-13/2n-15 < 0 /×2
n²-13-30<0
a=1
b=-13
c=-30
Δ=b²-4ac
Δ=-13²-4×1×(-30)
Δ=169+120
Δ=289
n₁=-b-√Δ /2a
n₂=-b+√Δ /2a
n₁=13-17 /2
n₂=13+17 /2
n₁=-2
n₂=15