dari kesamaan ax2 + (x + b)(2x – 1)=(bx – 2)(x + 3) + c, diperoleh ...

ax² + (x + b)(2x - 1)
= ax² + 2x² + 2bx - x + b
= (a+2)x² + (2b-1)x + b

(bx - 2)(x + 3) + c
= bx² + 3bx - 2x - 6 + c
= bx² + (3b-2)x + (-6+c)

maka
2b - 1 = 3b - 2
-1 + 2 = 3b-2b
1 = b
b = 1
b = a + 2
1 = a + 2
1 - 2 = a
a = -1
b = -6 + c
1 = -6 + c
1 + 6 = c
c = 7