1.应用换元积分法求下列不定积分-|||-(1) int cos (3x+4)dx;-|||-(2)int x(e)^2(x^2)dx;-|||-(3) int dfrac (dx)(2x+1);-|||-(4) int ((1+x))^ndx;-|||-(5) int (dfrac (1)(sqrt {3-{x)^2}}+dfrac (1)(sqrt {1-3{x)^2}})dx;-|||-(6) (int )(2)^2x+3dx;-|||-(7) int sqrt (8-3x)dx;-|||-(8) int dfrac (dx)(sqrt [3]{7-5x)}-|||-(9)int xsin (x)^2dx;-|||-(10) int dfrac (dx)({sin )^2(2x+dfrac (pi )(4))}-|||-(11) int dfrac (dx)(1+cos x)-|||-(12) int dfrac (dx)(1+sin x);-|||-(13)int cocodx;-|||-(14) int dfrac (x)(sqrt {1-{x)^2}}dx;-|||-(15) int dfrac (x)(4+{x)^4}dx;-|||-(16) int dfrac (dx)(xln x);-|||-(17) int dfrac ({x)^4}({(1-{x)^5)}^3}dx;-|||-(18) int dfrac ({x)^3}({x)^8-2}dx;-|||-(19) int dfrac (dx)(x(1+x));-|||-(20)int cot xdx;-|||-(21)int (cos )^5xdx;-|||-(22) int dfrac (dx)(sin xcos x)-|||-(23) int dfrac (dx)({e)^x+(e)^-x}-|||-(24) int dfrac (2x-3)({x)^2-3x+8}dx-|||-(25) int dfrac ({x)^2+2}({(x+1))^3}dx;-|||-(26) int dfrac (dx)(sqrt {{x)^2+(a)^2}}(agt 0);-|||-(27) int dfrac (dx)({({x)^2+(a)^2)}^3n}(agt 0);-|||-(28) int dfrac ({x)^5}(sqrt {1-{x)^2}}dx-|||-(29) int dfrac (sqrt {x)}(1-sqrt [3]{x)}dx;-|||-(30) int dfrac (sqrt {x+1)-1}(sqrt {x+1)+1}dx-|||-(31) int x((1-2x))^99dx;-|||-(32) int dfrac (dx)(x(1+{x)^n)} (n为自然数);-|||-(33) int dfrac ({x)^2n-1}({x)^n+1}dx;-|||-(34) int dfrac (dx)(xln xln ln x)-|||-(35) int dfrac (ln 2x)(xln 4x)dx;-|||-(36) int dfrac (dx)({x)^4sqrt ({x)^2-1}}