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given the following statement: the sum of 2 numbers namely 'a' and 'b' is equal to 'm' times their difference, and the product of those 2 numbers is 'n' times their difference.

we get the system:

a+b=m(a-b)
a*b=n(a-b)

and I'm able to decompose it like:

a+b=ma-mb
a*b=na-nb
.........
a=m(a-b)-b
b=m(a-b)-a
a=n(a-b)/b
b=n(a-b)/a

now, I know the answer is of the form:

a = 2n/m-1 and b = 2n/m+1

how is the process to solve this system of equations?

Nimi
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2 Answers2

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Hint: set $b=ka$ then the first equation gives you $k=\frac{m-1}{m+1}$ and proceed to solve the second equation.

When you have some equations like this, it is often useful to test things like $b=ka$ our $b=a+k$ and see if you can get something out of it.

zwim
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\begin{align} 4ab &=(a+b)^2-(a-b)^2\\ 4n(a-b) & =(a+b)^2-(a-b)^2\\ &= m^2(a-b)^2-(a-b)^2\\ &= (m^2-1)(a-b)^2\\ \implies (a-b) &=\dfrac{4n}{m^2-1} \text{, as obviously $a \ne b$}\\ \end{align}

Can you proceed from here?

Manjoy Das
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