Question

A student was asked to solve 3x^2−39x=0
by factoring out the GCF.

At what step did the student first make an error?

Given: 3x^2−39x=0

Step 1: 3x(x+13)=0

Step 2: 3x=0 and x+13=0

Step 3: x=0 and x=−13

(1 point)

Step 1

Step 2

Step 3

Answer 1

Step 1.

They factored incorrectly: 3x^2 − 39x = 3x(x − 13), not 3x(x + 13). This changes the second solution to x = 13 (not −13).