Question

if a+b+c=0,then prove that a square/bc

Answer 1

Since c = -(a+b), 

a²/(bc) + b²/(ca) + c²/(ab) 
= -a²/(b(a+b)) - b²/(a(a+b)) + (a+b)²/(ab) 
= [-a³ - b³ + (a+b)³] / (ab (a+b)) 
= (3a²b + 3ab²) / (ab (a+b)) 
= 3ab(a + b) / (ab (a+b)) 
= 3.