Q2 of 59 Page 7

Find the expansion of

(2x + 3)(2x – 5)(2x – 7)

(2x + 3)(2x – 5)(2x – 7)


Here we have to use the identity


(x + a)(x + b)(x + c) = x3 + (a + b + c)x2 + (ab + bc + ca)x + abc


∴ (2x + 3)(2x – 5)(2x – 7)


= (2x)3 + (3 – 5 – 7)(2x)2 + [(3)(– 5) + (– 5)(– 7) + (– 7)(3)](2x) + (3)(– 5)(– 7)


= 8x3 + (– 9)(4x2) + (– 15 + 35 – 21)(2x) + 105


= 8x3 – 36 x2 – 2x + 105


More from this chapter

All 59 →
2

Find the expansion of

(x – a)(x – 2a)(x – 4a)

 2

Find the expansion of

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

 3

Using algebraic identities find the coefficients of x2 term, x term and constant term.

(x + 7)(x + 3)(x + 9)

 3

Using algebraic identities find the coefficients of x2 term, x term and constant term.

(x – 5)(x – 4)(x + 2)