CTET 2 Math and Science 23 Dec 2021 Paper

Question : 44 of 151

Marks: +1, -0

In the product of

(2 x^2-5 x-4)

and

(x^2+7 x+8)

, if the coefficient of

x^2

is a, and the coefficient of

x

b

, then what is the value of (a - b ?

Solution:

(2 x^2-5 x-4)(x^2+7 x+8)

⇒(2 x^4+14 x^3+16 x^2-5 x^3-35 x^2-40 x-4 x^2-28 x-32)

⇒(2 x^4+9 x^3-23 x^2-68 x-32)

\;\text " Coefficient of "\; x^2=-23=a

\;\text " Coefficient of "\; x=-68=b

(a-b)=-23-(-68)

⇒-23+68=45

∴ a-b=45

The correct option is 3 i.e. is 45

Go to Question:

Prev Question

Next Question