Multiply and differentiate (3x+12)(1-7x)?

We'll use the the property of multiplication to be
distibutive over addition:

(3x+12)(1-7x) = 3x + 3x*(-7x) +
12*1 + 12*(-7x)

(3x+12)(1-7x) = 3x - 21`x^(2)` + 12 -
84x

We'll combine like
terms:

(3x+12)(1-7x) = -21`x^(2)` - 81x +
12

Now, we'll differentiate with respect to
x:

d(3x+12)(1-7x)/dx = -42x -
81

The requested result is d(3x+12)(1-7x)/dx
= -42x - 81.