Question

Identify the error in this column:
(x2 + 3x + 18) = (x + 3)(x + 6)

Answer 1

Answer:

I think the error is that the variable x came before the whole number 2.

Answer 2

$x^2+3x+18 = (x+3)(x+6)$

↝ The error here is that (x+3)(x+6) doesn't make 3x in the middle here.

↝ From (x+a)(x+b) = x²+bx+ax+ab = x²+(a+b)x+ab

Now we let a = 3 and b = 6

Let's check the answer.

Given a = 3 and b = 6 (From the polynomials given.)

(x+a)(x+b) = x²+(a+b)x+ab

(x+3)(x+6)=x²+(3+6)x+(3*6)

(x+3)(x+6)=x²+9x+18

As you can see that the error here is that (x+3)(x+6) doesn't make 3x in the middle of polynomial. Therefore the error here is only 3x as proven.