Question

Pre-calc! Help Please! For which intervals is the function y=3x^3-16x+2 increasing and decreasing?

Answer 1

The options are:
increasing for -2.31<x<2.31; decreasing for x<-2.31 and x>2.31
increasing for x<-4/3 and x>4/3; decreasing for -4/3<x<4/3
increasing for x<-2.31 and x>2.31; decreasing for -2.31<x<2.31
increasing for -4/3<x<4/3; decreasing for x<-4/3 and x>4/3

Answer 2

So looking at the graph I believe the answer is B or D, but don't know which one is correct...

Answer 3

@jim_thompson5910 ? or @Preetha does either of you guys know why one answer is right and which one is wrong and how to tell the difference!?

Answer 4

are you able to graph 3x^3-16x+2 ?

Answer 5

yes! :D

Answer 6

does that help you narrow your choices down?

Answer 7

Yes between B and D!

Answer 8

Heres the graphing calculator I use to confirm my graph. https://www.desmos.com/calculator

Answer 9

start off on the very left most part of the graph

then go to the right

are you going up? or down?

Answer 10

up then down