第一章1.6 1(2020玉溪模拟)计算(x)dx的值为(B)ABln2Cln2D3ln2解析(x)dx(x2lnx)|2ln2ln2；故选B2 (sinxcosx)dx的值是_2_.解析 (sinxcosx)dx(cosxsinx) 112.3若(2axa1)dx5，则a_1_.解析(2axa1)dx(ax2axx)|4a1，所以4a15，所以a1.4计算下列定积分：(1)(|x1|x2|)dx；(2)cos(2x)dx.解析(1)|x1|x2|(|x1|x2|)dx(32x)dx1dx(2x3)dx(3xx2)|x|(x23x)|5.(2)sin(2x)cos(2x)(2x)cos(2x)，cos(2x)dxsin(2x)sin(2)sin(20)(sinsin).
