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
In order to calculate the area of a triangular prism, You can use the formula,
Area = 1/2 * a * c * h
Hope this helps!
X>-6 is what i believe the answer is.
hope this helps!
Answer:
I am not sure if I'm correct, but I got 16
Step-by-step explanation:
lets look at the formula for cylinder volume:
V=π*r^(2)*h
now, lets plug in 64
64=π*r^(2)*h
h=64/(π*r^(2))
Volume of glass cylinder is
V=((0.5r)^2)*(64/(π*r^(2)))*π
V=0.25π*r^(2)*(64/(π*r^(2)))
V=16π*r^(2)/(π*r^(2)
V=16