The greatest common divisor of two positive integers less than $100$ is equal to $3$. Their least common multiple is twelve times one of the integers. What is the largest possible sum of the two integers?

Respuesta :

Answer:

129

Step-by-step explanation:

Let a and b be two numbers.

We have been given that the greatest common divisor of two positive integers less than 100 is equal to 3. We can represent this information as [tex]GCD(a,b)=3[/tex].

Their least common multiple is twelve times one of the integers. We can represent this information as [tex]LCM(a,b)=12a[/tex].

Now, we will use property [tex]GCD(x,y)*LCM(x,y)=xy[/tex].

Upon substituting our given values, we will get:

[tex]3*12a=ab[/tex]

[tex]36a=ab[/tex]

Switch sides:

[tex]ab=36a[/tex]

[tex]\frac{ab}{a}=\frac{36a}{a}[/tex]

[tex]b=36[/tex]

Now, we need to find a number less than 100, which is co-prime with 12 after dividing by 3.

The greatest multiple of 3 less than 100 is 99, but it is not co-prime with 12 after dividing by 3.

Similarly 96 is also not co-prime with 12 after dividing by 3.

We know that greatest multiple of 3 (less than 100), which is co-prime with 12, is 93.

Let us add 36 and 93 to find the largest possible sum of the required two integers as:

[tex]36+93=129[/tex]

Therefore, the required largest possible sum of the two integers is 129.