Q3 of 59 Page 7

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

(x – 5)(x – 4)(x + 2)

(x – 5)(x – 4)(x + 2)


Here we have to use the identity


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


∴ (x – 5)(x – 4)(x + 2)


= x3 + (– 5 – 4 + 2)x2 + {(– 5) × (– 4) + (– 4) × 2 + 2 × (– 5)}x + (– 5)(– 4)2


= x3 – 7x2 + (20 – 8 – 10)x + 40


= x3 – 7x2 + 2x + 40


Coefficient of


x2 = – 7


x = 2 and


Constant term = 40


More from this chapter

All 59 →
2

Find the expansion of

(2x + 3)(2x – 5)(2x – 7)

 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.

(2x + 3)(2x + 5)(2x + 7)

 3

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

(5x + 2)(1 – 5x)(5x + 3)