Inverse trigo

PLEASE SHOW THE WORKING

1. tan^-1(π/n) > π/6
Since, tan^-1x is an inc. function,
→ π/n > 1/√3
→ n < π√3
→ n < 5.44

2. Reduce the equation to y = 1 + 3x3 - x
(1, 2) and (2, 7) are the only integral ordered pairs.

3. Add and subtract both the equations. Then solve for x and y separately. You will get two values each for x and y. Plug them in the equations and see which pair satisfies both the equations simultaneously.