I want to define the derivative using y′=(u⋅v)′ , where y=(5x2+9)⋅(2x3+4) ;
Solution: According to the differentiation product rule for the case of functions u(x) and v(x) :
(u⋅v)′=u′⋅v+u⋅v′ , in our case, u(x)=5x2+9 ; u′=(5x2+9)′=10x ; and v(x)=2x3+4 ; v′=(2x3+4)′=6x2 ;
Then, y′=[(5x2+9)⋅(2x3+4)]′=10x⋅(2x3+4)+(5x2+9)⋅6x2=20x4+40x+30x4+54x2=50x4+54x2+40x .
Answer: y′=50x4+54x2+40x .