derivative of cos(2x^2-3)
Let's perform the differentiation: ddx(cos(2x2 -3))
Apply the differentiation rule: ddx(cos(f)) = -ddx(f)·sin(f) with f = 2x2 -3
ⓘ The derivative of cos(x) is -sin(x): ddx(cos(2x2 -3)) = -ddx(2x2 -3)·sin(2x2 -3)
-ddx(2x2 -3)·sin(2x2 -3)
ⓘ The derivative of a sum is the sum of the derivatives: ddx(2x2 -3) = ddx(2x2) + 0
-(ddx(2x2) + 0)·sin(2x2 -3)
ⓘ Adding 0 changes nothing: ddx(2x2) + 0 = ddx(2x2)■A constant factor stays in front of the derivative, (k*u)' = k*u': ddx(2x2) = 2·ddx(x2)■The derivative of x^n is n*x^(n-1): ddx(x2) = 2x
-2·2x·sin(2x2 -3)
ⅰ 2·2 = 4
▶Derivative:   -4x·sin(2x2 -3)