(3,3),(3,4),(4,1),(4,2),(4,3),故利用对称性知 dxdy 1⊥2 24+x2+ 26 29 + 32 37 44 42 49 0.196+0.371+0.343+0.312+0.177 0.329+0.302+0.154+0.285 2.470 Eev 即 9.880 √24+x2+ 下面计算积分的精确值: Tay 24x2+ 41n(y+√24+x+ 4ln(√25-x2+7)dx-2|ln(24+x2)d 0 由于 ln(24+x2)dx=dn(24+x2)-f 24 xln(24+x2)-2x+ 24 actg +C 从而 2|In(24+x2)dx =[2xln(24+x2)-4x+48 actg 24小}0