Add the following expressions : (i) – 17×2 – 2xy + 23y2, -9y2 + 15×2 + 7xy and 13×2 + 3y2 – 4xy (ii) – … a, b3 – 2a3 + b and -2b +…
Answers:
(i) (-17x2 – 2xy + 23y2) + (-9y2 + 15x2 + 7xy) + (13x2 + 3y2 – 4xy)
= – 17x2 – 2xy + 23y2 – 9y2 + 15x2 + 7xy + 13x2 + 3y2 – 4xy
= -17x2 + 15x2 + 13x2 – 2xy – 4xy + 7xy + 23y2 + 3y2 – 9y2
= 11x2 + xy + 17y2
(ii) (-x2 – 3xy + 3y2 + 8) + ( 3x2 – 5y2 – 3 + 4xy) + (-6xy + 2x2 – 2 + y2)
= – x2 – 3xy + 3y2 + 8 + 3x2 – 5y2 – 3 + 4xy – 6xy + 2x2 – 2 + y2
= – x2 + 3x2 + 2x2 – 3xy – 6xy + 4xy + 3y2 + y2 – 5y2 + 8 – 3 – 2
= 4x2 – 5xy – y2 + 3
(iii) (a3 – 2b3 + a) + (b3 – 2a3 + b) + (-2b + 2b3 – 5a + 4a3)
= a3 – 2b3 + a + b3 – 2a3 + b – 2b + 2b3 – 5a + 4a3
= a3 + 4a3 – 2a3 – 2b3 + b3 + 2b3 + a – 5a + b – 2b
= 3a3 + b3 – 4a – b