# Thread: I have a question.

1. ## I have several questions.

a is positive integer and b<13,

$\displaystyle \dfrac{a.b-b}{a}=7$

What is biggest value of b?

2. Originally Posted by OPETH
a is positive integer and b<13,

$\displaystyle \dfrac{a.b-b}{a}=7$

What is biggest value of b?
$\displaystyle \frac{ab-b}{a}=7$ re-arranges into $\displaystyle b = \frac{7a}{a-1}$.

The graph of b versus a is a hyperbola. Draw a graph and you'll see that the largest value of b that satisfies b < 13 and a is a positive integer is b = 21/2 corresponding to a = 3.

3. $\displaystyle b = \frac{7a}{a-1}$

and

if a=8

$\displaystyle b = \frac{7.8}{8-1}$ ,

$\displaystyle b = \frac{56}{7}$

$\displaystyle b = 8$

Thank you help.

4. Originally Posted by OPETH
$\displaystyle b = \frac{7a}{a-1}$

and

if a=8

$\displaystyle b = \frac{7.8}{8-1}$ ,

$\displaystyle b = \frac{56}{7}$

$\displaystyle b = 8$

Thank you help.
So b was also required to be an integer ....

5. $\displaystyle a.b-c=4$

$\displaystyle b.c-a=3$

in equality, a, b, c are positive integers.

What is total of $\displaystyle a+b+c$ minumum?

6. Originally Posted by OPETH
$\displaystyle a.b-c=4$

$\displaystyle b.c-a=3$

in equality, a, b, c are positive integers.

What is total of $\displaystyle a+b+c$ minumum?
Do not add a new question to an existing thread. Make a new thread.

7. Sorry since we don't have the possible answers we just can quess what b might be
b/(b-7)=a
a can go to extreme and so b can go to extreme as well