a(b+c)+d(b+c)=[tex]\sqrt{6}+ \sqrt{15}[/tex]<=> (a+d)(b+c)=[tex]\sqrt{6}+ \sqrt{15}[/tex] <=>([tex]\sqrt{5} + \sqrt{2})(b+c)[/tex] =[tex]\sqrt{6}+ \sqrt{15}[/tex]
b+c= [tex]\frac{ \sqrt{6} + \sqrt{15} }{ \sqrt{5}+ \sqrt{2} }[/tex]
b+c= [tex]\frac{ \sqrt{3} ( \sqrt{5} + \sqrt{2} )}{ \sqrt{5} + \sqrt{2} }[/tex]
Radical din 5 + radical din 2 se simpliifica<=> b+c= [tex]\sqrt{3}[/tex].
