# Who's up to the challenge? 76

Algebra Level 5

$(1+a)(1+b)(1+c)(1+d)\left( \frac { 1 }{ a } +\frac { 1 }{ b } +\frac { 1 }{ c } +\frac { 1 }{ d } \right)$

Find the minimum value of the above expression.

Note: $$a,b,c,d>0$$

×