S. 3 Factorization 有少少唔明

1a) Factorize c^2－8c－20
﹦(c－10)(c＋2)1b) Hence factorize y^2(y－3)^2－8y(y－3)－20Sub c = y(y - 3) to a) : y^2(y－3)^2－8y(y－3)－20= (y(y -3 ) - 10) (y(y - 3) + 2)= (y^2 - 3y - 10) (y^2 - 3y + 2)= (y - 5)(y + 2) (y - 1)(y - 2) 2a) Factorize the following expressions.
i) d^2＋2d－8
﹦(d－2)(d＋4)ii) d^2＋5d－14
﹦(d－2)(d＋7)2b) Hence factorize (﹣3d^2－6d＋24)＋(d^3＋5d^2－14d)﹦- 3 (d^2 + 2d - 8) + d(d^2 + 5d - 14) by part a) := - 3 (d - 2)(d + 4) + d(d - 2)(d + 7)= (d - 2)( - 3(d + 4) + d(d + 7))= (d - 2)(d^2 + 4d - 12)= (d - 2)(d - 2)(d + 6)﹦(d - 2)^2 (d + 6)