Question

9. Expand :

(i) (3x - 4y + 5z)² (ii) (2a-5b-4c)²
(iii)
(5x + 3y)³
(iv) (6a - 7b)³

Answer 1

Answer:

Explanation:
(i) (3x - 4y + 5z)^2
(a - b + c ) ^2 = a^2 + b^2 + c^2 - 2ab - 2bc + 2ca
9x^2 + 16y^2 + 25z^2 - 24xy - 40yz + 30zx

(ii) (2a - 5b - 4c)^2
(a - b - c)^2 = a^2 + b^2 + c^2 - 2ab + 2bc - 2ac
4a^2 + 25b^2 + 16c^2 - 20ab + 40bc - 16ac

(iii) (5x + 3y)^3
(a + b)^3 = a^3 + b^3 + 3ab(a+b)
125x^3 + 27y^3 + 3×5×3(5+3)
125x^3 + 27^3 + 360

(iv) (6a - 7b)^3
(a - b)^3 = a^3 - b^3 - 3ab(a-b)
216a^3 - 343b^3 - 3×6×7(6-7)
216a^3 - 343b^3 + 126