Explanation:
We are given:
![xy'=coty](https://img.qammunity.org/2020/formulas/mathematics/middle-school/aa4b0mznwbjbnrq3yc67f6so9dsfyrzaye.png)
This can be rewritten as
![x(dy)/(dx) =coty](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1wmc8r635m6rodlzn7547xxe8wq6t58rm0.png)
Next, we can bring the x's and y's to their respective sides by dividing by coty and x and then multiplying the dx to the other side. We can then change
into
. This gives us the differential
![tany\,dy=(1)/(x) \,dx](https://img.qammunity.org/2020/formulas/mathematics/middle-school/29oss9gniadjms264vfj891zwillqdl7xn.png)
Now we can integrate each side
![\int tan(y)\,dy=\int (1)/(x) \,dx](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mde21f3c1xpdz73okmh3fzbenuuxgp7omx.png)
To integrate tan(y), we need to manipulate it
![\int (sin(y))/(cos(y)) \,dy=\int (1)/(x) \,dx](https://img.qammunity.org/2020/formulas/mathematics/middle-school/t8n0nth5y6vq8yylep2717ygc1j4k053q8.png)
Now we can use u-substitution where
![u= cos(y)\\du=-sin(y) dy](https://img.qammunity.org/2020/formulas/mathematics/middle-school/p7eovx50uzerrb9m8u5rybbeufp2ced466.png)
This gives us
![-\int (1)/(u) \,du=\int (1)/(x) \,dx](https://img.qammunity.org/2020/formulas/mathematics/middle-school/walq5p6lkwusvvw38biv3yeb0gettcey97.png)
Now, lets integrate both sides
![-ln|u|=ln|x|+c](https://img.qammunity.org/2020/formulas/mathematics/middle-school/el5l4ijx17yxnx0bp03i0nqq9as1kdt9b8.png)
Next, we can substitute our u value back in
![-ln|cos(y)|=ln|x|+c](https://img.qammunity.org/2020/formulas/mathematics/middle-school/g25649trtvjcsg492xptpujvqn0zoiqwp7.png)
Now we can add
to the other side and subtract c from each side. This gives us
![C_2=ln|x|+ln|cos(y)|](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wsvds65vdgu8ovbrwbsosmuq4kd531qzjj.png)
Next, we can apply a property of logarithms to combine this sum of two logs into one log.
![C_2=ln|xcos(y)|](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ep37xam3uxr8a6yfds0ovkvv1ia3k5hk8t.png)
Lastly, we can add a base e to each side to remove the ln
![C_3=|xcos(y)|](https://img.qammunity.org/2020/formulas/mathematics/middle-school/hf4uqe8qn2cl3yqxi3uy7h1qmfmp02zpxi.png)
And here is our answer.