If sin−1x−x22+x34−…+cos−1x2−x42+x64−…=π2 for 0<|x|<2, then 100x equals
Since sin−1x+cos−1x=π2 for |x|≤1. ∴x−x22+x34−…=x2−x42+x64−… ⇒x1+x2=x21+x22(0<|x|<2) ⇒x2+x=x22+x2⇒2x+x3=2x2+x3⇒ x2 = x ⇒ x = 0, 1But x ≠ 0, ∴ x = 1.