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  1. Number of solutions of a trig-root equation ●●○○○ 20 ptsFind the number of real solutions xx of the equation sin⁡(πx4)+cos⁡(π2−x4)=2\sin\left(\frac{\pi\sqrt x}{4}\right)+\cos\left(\frac{\pi\sqrt{2-x}}{4}\right)=\sqrt 2.
  2. Sum of x and y in a system ●●●○○ 50 ptsGiven that x+sin⁡y=2008x+\sin y=2008 and x+2008cos⁡y=2007x+2008 \cos y=2007, where 0≤y≤π20 \leq y \leq \frac{\pi}{2}, find the value of x+yx+y. Give your answer as a decimal rounded to two decimal places.
  3. Maximum integer k in a derivative inequality ●●●●○ 100 ptsLet f(x)=ex−x−2f(x)=e^{x}-x-2. For x>0x>0, the inequality (x−k)f′(x)+x+1>0(x-k)f'(x)+x+1>0 always holds, where kk is an integer. Find the maximum value of kk.