Question

Expand the suares of the following

: a)5a+3b

: b)2x+1/x​

Answer 1

Answer:

(i) (2x + 1)3 As per Identity, (a + b)3 = a3 + b3 + 3ab(a + b) (2x + 1)3 = (2x)3 + (1)3 + 3(2x)(1)(2x + 1) = 8x3 + 1 + 6x(2x + 1) = 8x3 + 1 + 12x2 + 6x (2x + 1)3 = 8x3 + 12x2 + 6x + 1.

(ii) (2a – 3b)3 As per Identity, (a – b)3 = a3 – b3 – 3ab(a – b) (2a – 3b)3= (2a)3– (3b)3 – 3(2a)(3b)(2a-3b) = 8a3 – 27b3 – 18ab(2a – 3b) (2a – 3b)3= 8a3 – 27b3 – 36a2b + 54ab2

Answer 2

Answer:

(5a−3b)

3Using (a−b) 3

=a 3 −3ab(a−b)−b 3

=(5a) 3 −3(5a)(3b)(5a−3b)−(3b)

3=125a3−45ab(5a−3b)−27b3=125a 3

−225a b+135ab 2 −27b3

Hence, the answer is 125a 3 −225a 2

b+135ab 2−27b 3

hope it helps you