Find the z-intercept of the equation?

Question

Let z=(e^x)(cos(xy)). Find the z-intercept of the equation of the tangent plane to the surface at (1, pi/2, 0).

Answer 1

For a surface, z =f(x,y)

Eqn. of tangent plane at a point (x',y',z') is given by

f_x(x',y')(x-x') + fy(x',y')(y-y') - (z-z') = 0    where f_x and f_y are partial derivatives 

Once you have the equation use x=0 and y=0 to get your z intercept. 

Hope this helps.