(A) Use a+b=−11,ab=24
So, a=−3,b=−8
s2−11s+24=s2−3s−8s+24
=(s−3)(s−8)
(B) Divide 3x2−4x−7 by (x+1):
3x2−4x−7=3x2+3x−7x−7=3x(x+1)−7(x+1)=(3x−7)(x+1)
(3x−7)(x+1)=3x2−4x−7
(C) Split −11x using factors of 10×(−6)=−60:
−15+4=−11 and −15×4=−60
10x2−11x−6=10x2−15x+4x−6=5x(2x−3)+2(2x−3)=(2x−3)(5x+2)
(D) Split 7x using factors of 12:
3+46x2+7x+2=7,3×4=12=6x2+3x+4x+2=3x(2x+1)+2(2x+1)=(2x+1)(3x+2)