Review question

# Given this equation, what's the value of $a+b+c+d$? Add to your resource collection Remove from your resource collection Add notes to this resource View your notes for this resource

Ref: R6219

## Suggestion

Four positive integers $a$, $b$, $c$ and $d$ are such that $abcd+abc+bcd+cda+dab+ab+bc+cd+da+ac+bd+a+b+c+d=2009.$

What is the value of $a+b+c+d$?

Can we (almost) factorise the left hand side?

Or can we add something to the left hand side that means we can factorise it perfectly?