#1**+1 **

Possible derivation:

d/dx(-(5 a)/x^5 + 4 x)

Differentiate the sum term by term and factor out constants:

= -5 a (d/dx(1/x^5)) + 4 (d/dx(x))

Use the power rule, d/dx(x^n) = n x^(n - 1), where n = -5: d/dx(1/x^5) = d/dx(x^(-5)) = -5 x^(-6):

= 4 (d/dx(x)) - (-5)/x^6 5 a

Simplify the expression:

= (25 a)/x^6 + 4 (d/dx(x))

The derivative of x is 1:

= (25 a)/x^6 + 1 4

Simplify the expression:

**= 4 + (25 a)/x^6**

Guest Oct 1, 2017