derivative of sin(3x+1)
Let's differentiate: ddx(sin(3x + 1))
We differentiate using: ddx(sin(f)) = ddx(f)·cos(f) (where f = 3x + 1)
ⓘ The derivative of sin(x) is cos(x): ddx(sin(3x + 1)) = ddx(3x + 1)·cos(3x + 1)
ddx(3x + 1)·cos(3x + 1)
ⓘ The derivative of a sum is the sum of the derivatives: ddx(3x + 1) = ddx(3x) + 0
(ddx(3x) + 0)·cos(3x + 1)
ⓘ Adding 0 changes nothing: ddx(3x) + 0 = ddx(3x)■A constant factor stays in front of the derivative, (k*u)' = k*u': ddx(3x) = 3
▶Derivative:   3·cos(3x + 1)