Question

if ( x-1) (x^3 + x^2 - 2x) = x^4 + ax^3 + bx^2 + cx then the value of (a+b-c) is '; - a)1 b)2 c)3 d)4​

Answer 1

Answer:

Correct option is

B

−1

LHS=

(x−1)(x

2

+2)

2x

2

+3x+4

;RHS=

(x−1)(x

2

+2)

A(x

2

+2)+(Bx+C)(x−1)

LHS=RHS

2x

2

+3x+4=A(x

2

+2)+(Bx+C)(x−1)

Equating the co-efficients of power of x in LHS and RHS

A+B=2

−B+C=3

2A−C=4

Solving the equations, we get

A=3

B=−1

C=2

So, B=−1