When x → 0, α (x) = kx2 and β (x) = 1 + xarcsinx − cosx are equivalent infinitesimals, then K=______ .

When x → 0, α (x) = kx2 and β (x) = 1 + xarcsinx − cosx are equivalent infinitesimals, then K=______ .

According to the meaning of the title, limx → 0 β (x) α (x) = limx → 01 + xarcsinx − cosxkx2 = limx → 0xarcsinx + 1 − cosxkx2 (1 + xarcsinx + cosx) = 12klimx → 0xarcsinx + 1 − cosxx2 = 34k = 1  k = 34