¿Cómo diferenciamos (x ^ 2) sin (1 / x) usando el primer principio?

f (x) = x ^ 2sin (1 / x)

del primer director

f ‘(x) = lim h-> 0 [f (xh) -f (x)] / h

= lim h-> 0 {(xh) ^ 2sin [1 / (xh)] x ^ 2sin (1 / x)} / h

= lim h-> 0 {x ^ 2 [sin (1 / (xh)) – sin (1 / x)] + h ^ 2sin [1 / (xh)] 2xhsin [1 / (xh)]} / h

= lim h-> 0 {x ^ 2 [2cos [1/2 (1 / (xh) + 1 / x)] sin [1/2 (1 / (xh) -1 / x)]} / h +

{lim h-> 0 h * sin [1 / (xh)]} {lim h-> 0 2xsin [1 / (xh)]}

= lim h-> 0 {2x ^ 2cos [(x + xh) / (2x (xh))] sin [1/2 (x-x + h) / (x (xh))]} / h + 0 2xsin (1 / x)

= x ^ 2cos (1 / x) lim h-> 0 {sin [1/2 (h / (x (xh))] / [h / (x (xh)) * 2 (xh) x]} 2xsin (1 / x)

= x ^ 2cos (1 / x) * 1 * (x) x} 2xsin (1 / x) ; ya que lim h-> 0 {sin [1/2 (h / (x (xh))]] / [h / (x (xh))] = 1

f ‘(x) = cos (1 / x) -2xsin (1 / x)