関数 $y = (x - 1)(x^2 + 1)(2x - 1)$ を微分して、$dy/dx$を求める問題です。解析学微分関数の微分積の微分2025/7/51. 問題の内容関数 y=(x−1)(x2+1)(2x−1)y = (x - 1)(x^2 + 1)(2x - 1)y=(x−1)(x2+1)(2x−1) を微分して、dy/dxdy/dxdy/dxを求める問題です。2. 解き方の手順積の微分公式を繰り返し使用して解きます。まず、y=u(x)v(x)w(x)y = u(x)v(x)w(x)y=u(x)v(x)w(x) とおくと、y′=u′(x)v(x)w(x)+u(x)v′(x)w(x)+u(x)v(x)w′(x)y' = u'(x)v(x)w(x) + u(x)v'(x)w(x) + u(x)v(x)w'(x)y′=u′(x)v(x)w(x)+u(x)v′(x)w(x)+u(x)v(x)w′(x) となります。ここで、u(x)=x−1u(x) = x - 1u(x)=x−1、v(x)=x2+1v(x) = x^2 + 1v(x)=x2+1、w(x)=2x−1w(x) = 2x - 1w(x)=2x−1 とおくと、u′(x)=1u'(x) = 1u′(x)=1、v′(x)=2xv'(x) = 2xv′(x)=2x、w′(x)=2w'(x) = 2w′(x)=2 となります。したがって、y′=1⋅(x2+1)⋅(2x−1)+(x−1)⋅(2x)⋅(2x−1)+(x−1)⋅(x2+1)⋅2y' = 1 \cdot (x^2 + 1) \cdot (2x - 1) + (x - 1) \cdot (2x) \cdot (2x - 1) + (x - 1) \cdot (x^2 + 1) \cdot 2y′=1⋅(x2+1)⋅(2x−1)+(x−1)⋅(2x)⋅(2x−1)+(x−1)⋅(x2+1)⋅2=(x2+1)(2x−1)+2x(x−1)(2x−1)+2(x−1)(x2+1)= (x^2 + 1)(2x - 1) + 2x(x - 1)(2x - 1) + 2(x - 1)(x^2 + 1)=(x2+1)(2x−1)+2x(x−1)(2x−1)+2(x−1)(x2+1)=(2x3−x2+2x−1)+2x(2x2−3x+1)+2(x3−x2+x−1)= (2x^3 - x^2 + 2x - 1) + 2x(2x^2 - 3x + 1) + 2(x^3 - x^2 + x - 1)=(2x3−x2+2x−1)+2x(2x2−3x+1)+2(x3−x2+x−1)=(2x3−x2+2x−1)+(4x3−6x2+2x)+(2x3−2x2+2x−2)= (2x^3 - x^2 + 2x - 1) + (4x^3 - 6x^2 + 2x) + (2x^3 - 2x^2 + 2x - 2)=(2x3−x2+2x−1)+(4x3−6x2+2x)+(2x3−2x2+2x−2)=2x3−x2+2x−1+4x3−6x2+2x+2x3−2x2+2x−2= 2x^3 - x^2 + 2x - 1 + 4x^3 - 6x^2 + 2x + 2x^3 - 2x^2 + 2x - 2=2x3−x2+2x−1+4x3−6x2+2x+2x3−2x2+2x−2=(2x3+4x3+2x3)+(−x2−6x2−2x2)+(2x+2x+2x)+(−1−2)= (2x^3 + 4x^3 + 2x^3) + (-x^2 - 6x^2 - 2x^2) + (2x + 2x + 2x) + (-1 - 2)=(2x3+4x3+2x3)+(−x2−6x2−2x2)+(2x+2x+2x)+(−1−2)=8x3−9x2+6x−3= 8x^3 - 9x^2 + 6x - 3=8x3−9x2+6x−33. 最終的な答え8x3−9x2+6x−38x^3 - 9x^2 + 6x - 38x3−9x2+6x−3