CTET 2 Math and Science Sep 2016 Paper

Question : 49 of 150

Marks: +1, -0

In the product of

(9x^2 + 15 – x)

and

(–1– x + x^2)

, if A, B and c are the coefficients of

x^3, x^2

and x respectively, then the value of (A + B – C) is :

Solution:

The product of

(9x^{2}+15-x)

and

(-1-x+x^{2})

(9x^{2}+15-x)(-1-x+x^{2})=9x^{4}-10x^{3}+7x^{2}-14x-15

Since, A,B and C are the coefficients of

x^3,x^2

and x respectively.
Then

{A}=-10,{B}=7,{C}=-14

Now,

(A+B-C)=-10+7-(-14)

=-10+7+14

=-10+21

=11

Hence, the required value of

(A+B–C)

is 11.

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