Question

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

Answer 1

It should be 9x instead of 3x on the left-hand side of the equation.

Explanation:

We can expand the equation (x+3)(x+6) to find out:

(x+3)(x+6) = x² + 6x + 3x + 18

We multiply x with x then x with 6.

Then, we multiply 3 with x and 3 with 6.

x² + 6x + 3x + 18 = x² + 9x + 18

Answer 2

The error is found in the "3x" part of the equation.

Explanation:

The rest of the equation is correct because x times x = x2. And 6 times 3 = 18. But x times 6 = 6x, and 3 times x = 3x, and 6x+3x=9x. 9x doesn't = 3x