当y = - 2时- x² = - 2x = ± √2x = √2则= ∫(0→√2) (- x²) dx= - x³/3 |(0→√2)= - 2^(3/2)/3 + 0= - (2√2)/3面积 = |∫(0→√2) (- x²) dx| = (2√2)/3
