公式:(u/v)' = (vu'-uv')/v²
y' = {√(1-x²)*(1) - x*1/[2√(1-x²)]*(-2x)}/[√(1-x²)]²
= [√(1-x²) + x²/√(1-x²)]/(1-x²)
= [(1-x²)+x²]/√(1-x²) * 1/(1-x²)
= 1/(1-x²)^(3/2)
公式:(u/v)' = (vu'-uv')/v²
y' = {√(1-x²)*(1) - x*1/[2√(1-x²)]*(-2x)}/[√(1-x²)]²
= [√(1-x²) + x²/√(1-x²)]/(1-x²)
= [(1-x²)+x²]/√(1-x²) * 1/(1-x²)
= 1/(1-x²)^(3/2)