Find the general value of tn - find the domain of fxy -

Question

Question 1:

Solve the equation:

11x - 4y√(x²+1).dy/dx = 0

Question 2:

If t(x) = x sinx

t'(x) = dy/dx

Find the general value of tⁿ (x)

Question 3:

Solve the equation

(tan² θ-1)(2 cosθ+1) = 0

Question 4:

Solve the equation

10^2x - 18*10^x + 80 = 0

Question 5:

Find the domain of

f(x,y) = √y + √(16- x² - y²)