Math Quiz
Find the pair of three natural numbers which have an equal sum and product.
Hint: Let [tex]1\ \textless \ a\ \textless \ b\ \textless \ c[/tex], so that [tex]0\ \textless \ \dfrac{1}{c} \ \textless \ \dfrac{1}{b} \ \textless \ \dfrac{1}{a} \ \textless \ 1[/tex].
Given condition is [tex]abc=a+b+c[/tex]. …[I]
Let [tex]1\leq a\leq b\leq c[/tex]. …[II]
Divide [I] by [tex]c[/tex]
[tex]ab=\dfrac{a}{c} +\dfrac{b}{c} +1[/tex]
And by [II], [tex]0< \dfrac{a}{c} \leq \dfrac{b}{c} \leq \dfrac{c}{c} =1[/tex], we have [tex]1<ab<3[/tex]. Hence [tex]ab=2[/tex].
The first two numbers are [tex]\boxed{a=1, b=2}[/tex].
Now, all we have is an equation.
[tex]abc=a+b+c[/tex]
[tex]\rightarrow 2c=1+2+c[/tex]
[tex]\therefore \boxed{c=3}[/tex]
The pair of three numbers is [tex](a,b,c)=(1,2,3)[/tex].
Answer:
The pair of three numbers is (a,b,c)=(1,2,3)(a,b,c)=(1,2,3).