How to factorise 3x2-12x+3

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Ireally need subtract and simplify.(-y^2 – 4y - 8) – (-4y^2 – 6y + 3)show your work, ! i will mark you brainliest but you have to show your work.

Which of the following equations are equivalent to -2m - 5m - 8 = 3 + (-7) + m? -15m = -4m -7m - 8 = m - 4 -3m - 8 = 4 - m m - 4 = -7m - 8 -8 - 7m = -4 + m -8 - 3m = 4 - m