Looks like the equation is
![yy'+x=\sqrt{x^2+y^2}](https://tex.z-dn.net/?f=yy%27%2Bx%3D%5Csqrt%7Bx%5E2%2By%5E2%7D)
Substitute
, so that
. Then the equation is the same as
![\dfrac{u'-2x}2+x=\sqrt u\implies u'=2\sqrt u\implies\dfrac{\mathrm du}{2\sqrt u}=\mathrm dx](https://tex.z-dn.net/?f=%5Cdfrac%7Bu%27-2x%7D2%2Bx%3D%5Csqrt%20u%5Cimplies%20u%27%3D2%5Csqrt%20u%5Cimplies%5Cdfrac%7B%5Cmathrm%20du%7D%7B2%5Csqrt%20u%7D%3D%5Cmathrm%20dx)
Integrate both sides to get
![\sqrt u=C\implies\sqrt{x^2+y^2}=C](https://tex.z-dn.net/?f=%5Csqrt%20u%3DC%5Cimplies%5Csqrt%7Bx%5E2%2By%5E2%7D%3DC)
Given that
, we have
![\sqrt{1^2+(\sqrt8)^2}=C\implies C=3](https://tex.z-dn.net/?f=%5Csqrt%7B1%5E2%2B%28%5Csqrt8%29%5E2%7D%3DC%5Cimplies%20C%3D3)
so the solution is
![\sqrt{x^2+y^2}=3](https://tex.z-dn.net/?f=%5Csqrt%7Bx%5E2%2By%5E2%7D%3D3)
Answer:
b
Step-by-step explanation:
i just did it
The largest number that divides evenly into both 42 and 70 is 7.