A truck, P traveling at 54km/hr passes through a point at 10:30am, while
another truck, Q traveling at 90km/hr passes through this
same point 30 minutes later. At what time will truck Q overtake P?
For a, b, c, d ∈ R
a+b+c+d=0
ab, ac, ad, bc, bd, cd ≠0
Prove the inequality:
((ab)/((a+b)^2 ))+((ac)/((a+c)^2 ))+((ad)/((a+d)^2 ))+((bc)/((b+c)^2 ))+((bd)/((b+d)^2 ))+((cd)/((c+d)^2 ))≤−(3/2)
When is equality reached?