Question:
The sum of two natural numbers is 28 and their product is 192. Find the numbers.
Solution:
Let the required numbers be x and (28 − x).
According to the given condition,
$x(28-x)=192$
$\Rightarrow 28 x-x^{2}=192$
$\Rightarrow x^{2}-28 x+192=0$
$\Rightarrow x^{2}-16 x-12 x+192=0$
$\Rightarrow x(x-16)-12(x-16)=0$
$\Rightarrow(x-12)(x-16)=0$
$\Rightarrow x-12=0$ or $x-16=0$
$\Rightarrow x=12$ or $x=16$
When x = 12,
28 − x = 28 − 12 = 16
When x = 16,
28 − x = 28 − 16 = 12
Hence, the required numbers are 12 and 16.