She made the mistake of grouping unlike terms and factorizing.
Given that
Helene is finding the sum (9 + 10i) + (–8 + 11i).
She rewrites the sum as (–8 + 11)i + (9 + 10)i.
We have to determine
Which statement explains the property of addition that she made an error in using?
According to the question
The mistake she did is in the second term distributing.
(9+10i) is not equal to (9+10)i
Similarly (-8+11i) is not equal to (-8+11)i.
The correct method she should have done is given below;
Grouping real terms together and imaginary terms together and finding the sum is,
[tex]\rm = (9 + 10i) + (-8 + 11i)\\\\= 9+10i-8+11i\\\\= (9-8) +(10i+11i)\\\\=1+21i[/tex]
Hence, she made the mistake of grouping unlike terms and factorizing.
To know more about Complex Number click the link given below.
https://brainly.com/question/10078818
Answer:
D: Helene incorrectly used the distributive property by combining the real number and the coefficient of the imaginary part.
Step-by-step explanation:
