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,

Hence, she made the mistake of grouping unlike terms and factorizing.
To know more about Complex Number click the link given below.
brainly.com/question/10078818
It is a emergency # (number) for America and it is the day the twin towers were distroyed
Answer:
No
Step-by-step explanation:
y=7x
4=7(1)
4=7
This is not a true statement.
Answer:
21
Step-by-step explanation:
8 * 2 = 16
5 * 2 = 10
68 - 16 = 52 - 10 = 42.
The perimeter of the square is 42.
42 / 4 = 10.5. 10.5 is the length of a side.
10.5 * 2 = 21.
Answer:
It should be
A
F
D
Step-by-step explanation:
Just do A^2+B^2=C^2 and plug in what the three given numbers are, if A^2+B^2=C^2 and it comes out as correct meaning the sum of A and B is equal to C than boom you have a triple