Question

Factorise: (1) 27x^3 + 189x^2y 441xy^2+ 343y^3​

Answer 1

Answer:

I believe, there is a typographical error in the question, it should have been (3x + 7y) in stead of (3x - 7y).

(27x^3 + 343y^3)

= {(3x)^3} + {(7y)^3}

= (3x + 7y) * [{(3x)^2} - {(3x) * (7y)} + {(7y)^2}]

= (3x - 7y) * (9x^2 - 21xy + 49y^2)

So, A = 9, B = 49 and 7C = (-21); so, C = (-3).

Now, 4A - B + 5C = 36 - 49 - 15 = (-28).

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