Tolong bantuanya …

1. a.-3x^2-5xy+6x^2-2xy+7
   = 3x^2 -7xy +7
b.8a (-2a^2-3a) + 2ab -3a^2
=-16a^3-24a^2+2ab-3a^2
=-16a^3-27a^2+2ab

2. a.(5x^2-2xy+7)+(-3x^2+8xy-9)
=5x^2-2xy+7-3x^2+8xy-9
=2x^2+6xy-2
b.3b (a^2-2b)+ -5(a^2+3b)
=3a^2b-6b^2-5a^2-15b

3.3x^2-2xy-7-(-5x^2+2xy+8)
3x^2-2xy-7-5x^2-2xy-8
-2x^2-4xy-15