Solve 6x + 3) = 21. O A. x = -3 and x = -4
O B. x = 3 and x = -3
C. X = -3 and x = 4
D. X = 3 and x = -4
I need this ASAP

18x^2 - 9

Step-by-step explanation:

y = f(x)= 6x^3 - 9x + 4

dy/dx = d/dx(6x^3) - d/dx(9x) + d/dx (4)

=6.d/dx(x^3) - 9.d/dx (x) + d/dx. (4)

=6.3x^2 - 9.1 + 0 =18x^2 - 9

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.