2x²-7x+a
a= -8x+28
2x²-7x-8x+28
2x(x-4)-7(x-4)= (x-4)(2x-7)
4x²-ax+6
a= -(2+12)
4x²-(-(2+12))x+6
4x²-(-2-12)x+6
4x²+(2+12)x+6
4x²+2x+12x+6
2x(2x+1)+6(2x+1)= (2x+1)(2x+6)= 2(2x+1)(x+3)
2x²-7x+a
a= -8x+28
2x²-7x-8x+28
2x(x-4)-7(x-4)= (x-4)(2x-7)
4x²-ax+6
a= -(2+12)
4x²-(-(2+12))x+6
4x²-(-2-12)x+6
4x²+(2+12)x+6
4x²+2x+12x+6
2x(2x+1)+6(2x+1)= (2x+1)(2x+6)= 2(2x+1)(x+3)