A student wants to determine how his classmates feel about school. He does a survey away from school so all participants will be willing to answer freely. In several cases, younger siblings of his classmates are
present, so he lets them take the survey too. He surveys a total of 50 students. Has he done a well-
designed, controlled experiment? Select the correct answer.

plato users:

d.  

there was a variety of food available on island x, but there were only large seeds and nuts on island y.

answer-

the statement that f(x) = |x+a| + b has exactly one x-intercept is sometimes correct.

solution-

it solely depends on b, whether the function will have one or two or zero x intercept.

this plot of the given function, f(x) = |x+a| + b will be the basic absolute value graph i.e v shape, with vertex translated to (-a, b), instead of origin.

1-   if b is zero, the graph will have exactly one x-intercept, at x= -a

2- if b is positive, the whole graph will be above the x-axis, hence it will have no x-intercepts.

3- if b is negative, the graph will be below the x-axis, hence it will have two x-intercepts.

∴ the statement is sometimes true.

not always but somethings can be reproduced in a laboratory.