Question

Se stie ca: ab+ac+ad=2005
si b+c+d=401,aflati ,,a''

Answer 1

$ab+ac+ad=2005\\\\a\cdot(b+c+d)=2005\\\\401\cdot a=2005\\\\a=\boxed{\boxed{5}}$

Answer 2

Dai factor comun pe a:
ab+ac+ad = a*(b+c+d) 
=> a=2005/(b+c+d)
a=2005/401
a=5
:D