Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
126 Elementos de cálculo, volumen 1<br />
Solución: En lo que sigue verifique usted qué propiedades se usan en<br />
cada caso:<br />
1. f ′ (x) = (8x 4 ) ′ = 8(x 4 ) ′ = 8 · 4x 3 = 32x 3<br />
2. g ′ (x) = (x 5 + x 3 ) ′ = (x 5 ) ′ + (x 3 ) ′ = 5x 4 + 3x 2<br />
3. h ′ (x) = (x 6 − 123) ′ = (x 6 ) ′ − (123) ′ = 6x 5 − 0 = 6x 5<br />
4. p ′ (x) = [(x −4 ) √ x] ′ = (x −4 ) ′√ x + (x −4 )( √ x) ′ =<br />
−4x −5√ x + x −4 · 1<br />
2 √ x<br />
5. r ′ <br />
x3 (x) =<br />
x2 + 1<br />
′<br />
= 3x2 (x 2 + 1) − x 3 (2x)<br />
(x 2 + 1) 2<br />
= (x3 ) ′ (x 2 + 1) − x 3 (x 2 + 1) ′<br />
(x 2 + 1) 2<br />
= 3x4 + 3x 2 − 2x 4<br />
(x 2 + 1) 2<br />
=<br />
= x4 + 3x 2<br />
(x 2 + 1) 2<br />
6. s ′ (x) = [(x 5 + 4x) 15 ] ′ = 14(x 5 + 4x) 14 · (x 5 + 4x) ′ =<br />
14(x 5 + 4x) 14 · (5x 4 + 4)<br />
Ejemplo 37.<br />
Calcular la derivada de las siguientes funciones<br />
1. q(x) = 2x 5 + 4x 3 + 2x.<br />
2. f(x) = (x 5 − 2x 3 )(x 14 + 15x 2 + 6x)<br />
3. g(t) =<br />
t + 1<br />
t 2 − 3t + 1<br />
4. h(t) = 3√ t 3 + 5t − 4<br />
Solución:<br />
1. q ′ (x) = (2x 5 + 4x 3 + 2x) ′ = 10x 4 + 12x 2 + 2.<br />
2. f ′ (x) = [(x 5 − 2x 3 )(x 14 + 15x 2 + 6x)] ′ =<br />
(5x4 − 6x2 )(x14 + 15x2 + 6x) + (x5 − 2x3 )(14x13 + 30x + 6)<br />
3. g ′ <br />
t + 1<br />
(t) =<br />
t2 ′<br />
=<br />
− 3t + 1<br />
1(t2 − 3t + 1) − (t + 1)(2t − 3)<br />
(t2 − 3t + 1) 2 .<br />
Note que aquí se utilizó la letra t como variable independiente.<br />
△