∫012x(x2+1)3 dx=\displaystyle\int_0^1 2x(x^2+1)^3\,dx =∫012x(x2+1)3dx=A444B14\tfrac{1}{4}41C154\tfrac{15}{4}415check_circleD164\tfrac{16}{4}416Explanationu=x2+1u = x^2 + 1u=x2+1. When x=0,u=1x = 0, u = 1x=0,u=1; x=1,u=2x = 1, u = 2x=1,u=2. ∫12u3 du=[u4/4]12=4−1/4=15/4\int_1^2 u^3\,du = [u^4/4]_1^2 = 4 - 1/4 = 15/4∫12u3du=[u4/4]12=4−1/4=15/4.