f(x,y)=x^2+2y^2

use the gradient vector �Þf(5, 1) to find the tangent line to the level curve f(x, y) = 27 at the point (5, 1).
answer choices:
1. 10x + 4y = 27
2. 2x + 4y = 27
3. 5x + 2y = 27
4. 10x − 4y = 27
5. 5x − 2y = 27