# Exact equation

• Feb 9th 2010, 02:38 PM
steph3824
Exact equation
I already know this equation is not exact. The thing is, I never learned how to do partial derivatives so that is what I need help with. The equation is \$\displaystyle (e^xsiny+3y)dx-(3x-e^xsiny)dy=0\$
I know that the sign in the middle needs to be + so then you have \$\displaystyle (e^xsiny+3y)dx+(-3x+e^xsiny)dy=0\$.
Then M=\$\displaystyle e^xsiny+3y\$ and N=\$\displaystyle -3e^x+e^xsiny\$. So, I need help getting \$\displaystyle M_y and N_x\$.
• Feb 9th 2010, 03:04 PM
firebio
Quote:

Originally Posted by steph3824
I already know this equation is not exact. The thing is, I never learned how to do partial derivatives so that is what I need help with. The equation is \$\displaystyle (e^xsiny+3y)dx-(3x-e^xsiny)dy=0\$
I know that the sign in the middle needs to be + so then you have \$\displaystyle (e^xsiny+3y)dx+(-3x+e^xsiny)dy=0\$.
Then M=\$\displaystyle e^xsiny+3y\$ and N=\$\displaystyle -3e^x+e^xsiny\$. So, I need help getting \$\displaystyle M_y and N_x\$.

To do partial derivatives, just hold all other variables that u r not taking the derivative constant

So
\$\displaystyle M_y = e^xcosy+3 \$
and
\$\displaystyle N_x = -3e^x+e^xsiny \$