Why did Paolo add 3(x + 2) to itself and subtract 8?

The pyramid below was dissected by a horizontal plane which shape describes the pyramid horizontal cross section

Prove that (x-2)is factor of p (x)=2x³-3x²-17x+30

Worth 100 points need the answers asap first row -x^2 2x^2 (x/2)^2 x^2 x is less than 2 x is greater than 2 x is less than or equal to 2 x is greater than or equal to 2 second row -5 -5/2 4 5 •2 is less than x& x is less than 4 •2 is less than or equal to x & x is less than or equal to 4 •2 is less than or equal to x& x is less than 4 •2 is less than x& x is less than or equal to 4