Answer:
-4 1/4
Step-by-step explanation:
-7 3/4 + 3 1/2 = -4 1/4
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
To find the standard error, divide the standard deviation by the square root of the sample size
standard deviation = 7.5
sample size = 25......sqrt 25 = 5
standard error = 7.5 / 5 = 1.5 <==
Value of x is 35°
Step-by-step explanation:
- Step 1: Since the line segment is a perpendicular bisector, the angle formed is equal to 90° and two triangles are also formed.
Find x using the property of triangles that sum of angles of a triangle is 180°
⇒ x° + 55° + 90° = 180°
⇒ x° + 145° = 180°
∴ x = 180 - 145 = 35°