1-5-27
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When trying to find the original function for this one, we have
the quantity of X plus YE to the YDYDX equalling one.
We could distribute the DY to the DYDX to the two terms, but
we need to get it in a form that we're familiar with.
So we really want DYDX to have A1 coefficient eventually minus
the Y variable times some coefficient.
So when we look at this, we can see that's not going to be
easily done.
So instead of doing it in dy DX, let's try to do it in DX dy.
So the first thing we're going to do is we're going to multiply
each side by DX dy.
Then we can see I can subtract the single X over, and now I
have DX dy with A1 coefficient minus something times a plain
old X equaling YE to the Y.
So now we're going to figure out what our row is.
So this time it's going to be row of Y instead of row of X
equaling E to the integral -1 the coefficient on the X term
DY.
So when we evaluate that, we get E to the negative Y, then we're
going to take that term and we're going to multiply it all
the way through.
So now we have E to the negative YDYD X -, e to the negative yx
equaling Y because the E to the Y and the E to the negative Y
are going to cancel, giving us one.
Now the two terms on the left hand side are really going to be
the product rule for E to the negative yx, taking the
derivative in terms of Y.
So ddy of E to the negative yx is going to equal plane Y.
We're going to take and we're going to evaluate the integral
of each side.
Remember fundamental theorem of calculus as the integral of a
derivative are going to cancel.
So we get E to the negative yx equaling the integral of YDY.
Add 1 to the exponent, divide by the new exponent on the right
hand side and make sure to add the constant.
So then to get X by itself, we're going to multiply in the
entire equation through by east to the Y or divide it by east to
the negative Y.
For final answer of X equal 1 half y ^2 east to the Y + C, E
to the Y.