Question

Find the coefficients of x in expansion of (x + 3)2
.

Answer 1

Answer:

Correct option is

D

12

We know that the formula for (a+b)

3

is:

(a+b)

3

=a

3

+b

3

+3a

2

b+3ab

2

Now, let us substitute a=x and b=2 in the above formula as shown below:

(x+2)

3

=x

3

+2

3

+(3x

2

×2)+(3x×2

2

)

=x

3

+8+6x

2

+(3x×4)

=x

3

+8+6x

2

+12x

=x

3

+6x

2

+12x+8

From the above calculations, we observe that the coefficient of x

3

is 1, coefficient of x

2

is 6 and coefficient of x is 12.

Hence, the coefficient of x is 12.

Answer 2

Answer:

the co efficient is 9 as per the way the calculation