The answer is 2x(2x²+x+1).
When we subtract polynomials we combine like terms:
(9x³+2x²-5x+4)-(5x³-7x+4)
9x³-5x³=4x³
2x²- 0 = 2x²
-5x--7x=-5x+7x=2x
4-4=0
This gives us
4x³+2x²+2x
Each of these is divisible by 2, and each has an x, so we factor those out:
2x( )
4x³/2x = 2x²:
2x(2x² )
2x²/2x=x:
2x(2x²+x )
2x/2x = 1:
2x(2x²+x+1)
