Considering the situation described, the scientist's null and alternative hypothesis are described by:
Null hypothesis
; Alternative hypothesis
.
<h3>What are the hypothesis tested?</h3>
At the null hypothesis, it is tested if there is no difference, that is, the difference of the means represented by
is of 0, hence:

At the alternative hypothesis, it is tested if there is a difference, hence:

More can be learned about an hypothesis test at brainly.com/question/26454209
Like terms are when numbers with and without variables can be combined. ex: 4x+6-8x+=32
you would first combine 4x and -8x because they are the same.
Option D. 2(n + 9) is the right answer
Step-by-step explanation:
The word problems are converted into mathematical problems to solve simply.
for the given problem
"two times the sum of a number and 9"
Let n be a number then
when there is and between two things they are performed first then next operation is performed so
the sum of a number and 9

Then
two times the sum of a number and 9

Hence,
Option D. 2(n + 9) is the right answer
Keywords: Mathematical notation
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Step-by-step explanation:
the second one as the -2x-3 is only on the second one