(10b+4)+(6-9b)-(3b-7)=
= 10b +4 + 6 - 9b - 3b +7
= - 2b + 17 RESULTADO FINAL
20+(-7+2x)-(-3x-7)=
= 20 - 7 + 2x + 3x + 7
= 20 + 5x RESULTADO FINAL
-3/4 a2+1/2 ab -5/6 b2 +21/3a2 -3/4ab +1/6b2 -1/3b2 -2ab =
= (- 3/4a^2 + 21/3a^2) + (- 5/6b^2 + 1/6b^2 - 1/3b^2) + (1/2ab - 3/4ab - 2ab)
= (- 9/12 + 84/12)a^2 + (- 5/6 + 1/6 - 2/6)b^2 + (2/4 - 3/4 - 8/4)ab
= 75/12a^2 - 6/6b^2 - 9/4ab
= 25/4a^2 - b^2 - 9/4ab RESULTADO FINAL
