Differentiation with respect to x' of the following function:

Question

(1) (x2-5x+6) (x-3)

Answer 1

did you mean
y = (x^2 - 5x+6)(x-3) ?

For this one, I would have actually expanded it.
y = x^3 - 3x^2 - 5x^2 + 15x + 6x - 18
= x^3 - 8x^2 + 21x - 18

dy/dx = 3x^2 - 16x + 21

or .... by the product rule:
dy/dx = (x^2 - 5x + 6)(1) + (2x - 5)(x-3)
= x^2 - 5x + 6 + 2x^2 - 6x - 5x + 15
= 3x^2 - 16x + 21

Answer 2

Thankyou sir