Question

A student expanded an expression, as shown. Is the student's work correct? Explain why or why not.

−6 ( 4x −
2
13
)

−6(4x) + 6 ( −
2
13
)

−24x −
12
13

Answer 1

The student's work is incorrect because the student didn't distribute all through with -6.

Explanation:

Let us expand the given expression to see whether the student made a mistake or not, and where the mistake was made, if there was any.

`-6(4x - (2)/(13))`

To expand, distribute -6

`-6(4x) - 6(-(2)/(13))` (check the work of the student at this step. This is where the student made a mistake. The student used +6 to multiply the 2nd term in the bracket instead of -6)

`-24x + (12)/(13))` (negative multiply by negative equals positive).

The work of the student is incorrect because the student didn't distribute -6 all through. The student used -6 for the first term, and also used +6 for the second term in the parentheses.