Please help math terms

Asequence has a common ratio of and f(5) = 81. which explicit formula represents the sequence? f(x) = 24 f(x) = 16 f(x) = 24 f(x) = 16

Rachel is studying the population of a particular bird species in a national park. she observes every 10th bird of that species that she can find in the park. her conclusion is that the birds living in the park who belong to that species generally feed on insects. rachel's sample is . based on the sample she picked, rachel's generalization is

The function below is written in vertex form or intercept form. rewrite them in standard form and show your work. y = -3(x-2)(x-4)