Exercise48. 0. 2aa+b. 7a1−a2. x−10y4x2−25y2. 2x+4y. 2(x+6)4x2−9. Exercise49. 203bc. 2ay3. 7p24xz. 2a2cm7. 30abc. abc. b2. x+ax−2a. xy2c−1. a+10a+3. 3x+2yx−2. 5a+b4a+3b. x−7a+b+c.