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Differential equations

FurtherMaths2020

why is it (+-) in the answer: y = (+-)(A/X)?

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Reply 1

mqb2766

Original post by FurtherMaths2020

why is it (+-) in the answer: y = (+-)(A/X)?

The "obvious" answer is because it has the modulus or absolute value sign around xy, so you have to handle both pos and neg solutions.

More instructive would be to sketch (or plot) the two curves, where A>0,
y = A/x
y = -A/x
and check they satisfy the original diff eqn?

When you have products (or division) of variables like this, you have to be careful about multiplying (or dividing) signs