∫dxx154+x4512
1+x4/5+c
521+x4/5+c
x4/5(1+x4/5)1/2+c
251+x4/5+c
∫dxx154+x4512 =∫5dt4t12 Let 4+x45=t⇒4/5x1/5dx=dt
=54t×2+C =52×1+x4512+C