How do you integrate int xsqrt(4-x)x4x using substitution?

1 Answer
Nov 3, 2016

int color(white)(.)xsqrt(4-x)color(white)(.) dx = -2/15(3x+8)(4-x)^(3/2) + C.x4x.dx=215(3x+8)(4x)32+C

Explanation:

Let u = 4-xu=4x

Then du = -dxdu=dx

int color(white)(.)xsqrt(4-x)color(white)(.) dx = int color(white)(.)(u-4)sqrt(u)color(white)(.) du.x4x.dx=.(u4)u.du

color(white)(int color(white)(.)xsqrt(4-x)color(white)(.) dx) = int color(white)(.)u^(3/2) - 4 u^(1/2)color(white)(.) du.x4x.dx=.u324u12.du

color(white)(int color(white)(.)xsqrt(4-x)color(white)(.) dx) = 2/5 u^(5/2) - 8/3 u^(3/2) + C.x4x.dx=25u5283u32+C

color(white)(int color(white)(.)xsqrt(4-x)color(white)(.) dx) = 2/5 (4-x)^(5/2) - 8/3 (4-x)^(3/2) + C.x4x.dx=25(4x)5283(4x)32+C

color(white)(int color(white)(.)xsqrt(4-x)color(white)(.) dx) = (2/5 (4-x) - 8/3)(4-x)^(3/2) + C.x4x.dx=(25(4x)83)(4x)32+C

color(white)(int color(white)(.)xsqrt(4-x)color(white)(.) dx) = 2/15(3 (4-x) - 20)(4-x)^(3/2) + C.x4x.dx=215(3(4x)20)(4x)32+C

color(white)(int color(white)(.)xsqrt(4-x)color(white)(.) dx) = -2/15(3x+8)(4-x)^(3/2) + C.x4x.dx=215(3x+8)(4x)32+C