y'= (3x^5 - 7x³)' = (3x^5)'-( 7x³)' = 3*5x^4-7*3x^2=15x^4 -21x^2
y'= (x³(x²-1))' = (x^5-x^3))' = (x^5)'-( x³)' = 5x^4-3x^2 = (5x^2-3)*x^2
y'= (1/2 sinx)' = 1/2 (sinx)' =1/2 cosx
y'= (3x^5 - 7x³)' = (3x^5)'-( 7x³)' = 3*5x^4-7*3x^2=15x^4 -21x^2
y'= (x³(x²-1))' = (x^5-x^3))' = (x^5)'-( x³)' = 5x^4-3x^2 = (5x^2-3)*x^2
y'= (1/2 sinx)' = 1/2 (sinx)' =1/2 cosx