<span>Let's analyze Hannah's work, step-by-step, to see if she made any mistakes.
</span>In Step 1, Hannah wrote
<span> as the sum of two separate derivatives </span>
<span>using the </span><span>sum rule.
</span>
This step is perfectly fine.
In Step 2,
was kept as it is, and 
was rewritten as 
using the constant rule.Indeed, according to the constant rule, the derivative of a constant number is equal to zero.
This step is perfectly fine.
In Step 3,
was rewritten as 
supposedly using the constant multiple rule.
The problem is that according to the constant multiple rule,
should be rewritten as 
and not as 
.
<span>Therefore, Hannah made a mistake in this step.</span>
</span>In Step 1, Hannah wrote
</span>
This step is perfectly fine.
In Step 2,
This step is perfectly fine.
In Step 3,
The problem is that according to the constant multiple rule,
<span>Therefore, Hannah made a mistake in this step.</span>