/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q. 3 Sign analyses: For each of the f... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Sign analyses: For each of the following functions g(x),use algebra and a sign chart to find the intervals on which g(x) is positive and the intervals on which g(x) is negative.

ag(x)=6x2−18xbg(x)=2−x−2x2+x3cg(x)=(x+2)(x−1)4exdg(x)=3x2−5x−2sin2x

Short Answer

Expert verified

Part (a) The given function is positive in the intervals (−∞,0)and(3,∞),and negative in the interval (0,3).

Part (b) The given function is positive in the intervals (−1,1)and(2,∞),and negative in the intervals (−∞,−1)and(1,2).

Part (c) The given function is positive in the interval (2,∞),and negative in the interval (−∞,−2).

Part (d) The given function is positive in the intervals role="math" localid="1649925937220" (−∞,1)and(23,∞),and negative in the interval 1,23.

Step by step solution

01

Part (a) Step 1. Given Information.

The given function isg(x)=6x2-18x.

02

Part (a) Step 2. Find the intervals.

The given function is positive for the values of xwhen g(x) > 0,and negative for the values of xwhen g(x) < 0.

Now, to find the intervals put g(x) = 0,

g(x)=6x2-18x0=6xx-3x=0andx=3

Sign chart of the function is

Intervalx(x - 3)g(x)
x > 3 +++
0 +--
x < 0--+

Thus, the function is positive in the intervals (−∞,0)and(3,∞),and negative in the intervals0,3.

03

Part (b) Step 1. Find the intervals. 

The given function is positive for the values of xwhen g(x) > 0,and negative for the values of xwhen g(x) < 0.

Now, to find the intervals put g(x) = 0,

g(x)=2-x-2x2+x30=2-x-2x2+x30=x-1x+1x-2x=1,x=-1,andx=2

Sign chart of the function is

Interval(x-2)(x - 1)(x + 1)g(x)
x < -1 ----
-1 --++
1 -++-
x > 2 ++++

Thus, the function is positive in the intervals (−1,1)and(2,∞),and negative in the intervals(−∞,−1)and(1,2).

04

Part (c) Step 1. Find the intervals. 

The given function is positive for the values of xwhen g(x) > 0,and negative for the values of xwhen g(x) < 0.

Since the function exand(x−1)4 are always on the real line, thus g(x) > 0,

x+2>0x>-2

And g(x) < 0,

x+2<0x<-2

Sign chart of the function is

Interval(x-2)g(x)
x < -2 --
-2 < x < 1 --
1--
x > 2++

Thus, the function is positive in the interval (2,∞),and negative in the interval(−∞,−2).

05

Part (d) Step 1. Find the intervals. 

The given function is positive for the values of xwhen g(x) > 0,and negative for the values of xwhen g(x) < 0.

Since the function sin2x are always on the real line, g(x) > 0 andg(x) < 0,

3x2-5x-2>0x-13x-2>0And3x2-5x-2<0x-13x-2<0

To find the intervals let's put g(x) = 0,

x-13x-2=0x=1andx=23

Sign chart of the function is

Interval(x-1)x-233x2-5x-2g(x)
x < 1 --++
1<x<23 +---
23<x<8++++

Thus, the function is positive in the intervals (−∞,1)and(23,∞)and negative in the interval1,23.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Study anywhere. Anytime. Across all devices.