Question

The coefficient of x² in (3x² – 5)( 4 +4x²) is:

8
-8
-3
3​

Answer 1

$\huge\boxed{\blue{Solution}}$

$(3 {x}^{2} - 5)(4 + 4 {x}^{2} )$

$(3 {x}^{2} \times 4) + (3 {x}^{2} \times 4 {x}^{2} ) + ( - 5 \times 4) + ( - 5 \times 4 {x}^{2} )$

$12 {x}^{2} + 12 {x}^{4} - 20 - 20 {x}^{2} \\ \\ - 8 {x}^{2} + 12 {x}^{4} - 20$

Thus, the cofficient of x² is -8

#BeBrainly

Answer 2

The coefficient of x² in (3x² – 5)( 4 +4x²) is -8.

Solution,

The coefficient of a number can be defined as a number that is multiplied by a variable. For example coefficient of x² in expression, 6x²+99 is 6.

Let us first expand the given expression by multiplying the terms by opening the brackets.

⇒   (3x² – 5)( 4 +4x²)

Now, further multiplying we would get,

⇒   3x²(4 + 4x²) -5(4 + 4x²)

⇒   $12x^{2}+12x^{4}-20-20x^{2}$  

⇒   $12x^{4}-20-8x^{2}$.

As we can see that the term that is in multiplication with x² is -8. Similarly, the term that is coefficient of  $x^{4}$ is +12.

Hence, the coefficient of x² in the equation $12x^{4}-20-8x^{2}$ is -8.