What is the equivalent factored form of 12x4 - 42x3 - 90x2? 6x (x - 5) (2x + 3) 6x2 (x - 5) (2x + 3) 6x (x + 5) (2x - 3) 6x2 (x + 5) (2x - 3)

B. Factor out x^2 first. 12*x^4-42*x^3-90*x^2 = (x^2) * (12*x^2-42*x-90). See that 6 is a common divisor of 12, 42, 90, so factor out 6: (6x^2) * (2*x^2-7*x-15). Then factor (2x^2-7x-15) as (2x+3) * (x-5). So the original expression = (6x^2) (2x+3) * (x-5)