Question

On which interval(s) is f(x)= x^4-2x^2-7 decreasing?

Answer 1

do you know how to take derivatives?

Answer 2

and about critical numbers?

Answer 3

@Jbo11 I got -1, 0, 1

Answer 4

I know I plot those on a graph, what do I do from there?

Answer 5

once you find the criticals I have been taught to write a table

Answer 6

where did you get the -100, -0.5, 0.5, and 100? also, I plug in the intervals back into the original equation?

Answer 7

the critical numbers give you intervals, you need -infinity to the lowest critical number, then the lowest critical number to the next number etc. Then you use test numbers (numbers between the critical numbers) and plug them into f(x), and if positive it increases and negative decreases. This is how I learned it, and it works

Answer 8

ok great! thank you so much!

Answer 9

np, hope that made sense