Q. 2 E5.0( 3 Votes )

# Find the expansion of

(3x + 1)(3x + 2)(3x + 5)

Answer :

(3x + 1)(3x + 2)((3x + 5)

Here we have to use the identity

(x + a)(x + b)(x + c) = x^{3} + (a + b + c)x^{2} + (ab + bc + ca)x + abc

∴ (3x + 1)(3x + 2)((3x + 5)

= (3x)^{3} + (1 + 2 + 5)(3x)^{2} + (1 × 2 + 2 × 5 + 5 × 1)(3x) + 1 × 2 × 5

= 27 x^{3} + (8)9x^{2} + (2 + 10 + 5) (3x) + 1 × 2 × 5

= 27 x^{3} + 72x^{2} + 51x + 10

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