Question

Can someone plx help me?
-|3x + 4| = 5x + 4

Answer 1

\[-\left|3x+4\right|=5x+4\quad :\quad x=-1\]

Answer 2

|3x+4|=-(5x+4)

anyways you have two equations to solve:
3x+4=-(5x+4) or also 3x+4=5x+4

then check solutions

Answer 3

so one is 2x = 0?

Answer 4

and one is x=1?

Answer 5

i think the 1st oneis wrong

Answer 6

@Ibbutibbu. i am right x=-1

Answer 7

one solution you will see not work out because both sides will not be the same

Answer 8

@DecentNabeel he might want to know how to get the solution

Answer 9

yeah ^^^

Answer 10

\[3x+4=-(5x+4) \\ 3x+4=-5x-4 \\ 3x+5x=-4-4 \\ 8x=-8 \\ x=-1 \\ \text{ then also } 3x+4=5x+4 \\ 3x-5x=4-4 \\ -2x=0 \\ x=0 \]
we can check both of these to see if they are actually solutions

Answer 11

but plugging them into the original equation

Answer 12

\[-|3x+4|=5x+4 \\ \text{ for example are both of these true: } \\ -|3(-1)+4|=5(-1)+4 \\ -|3(0)+4|=5(0)+4\]

Answer 13

if not which is true

Answer 14

i think they are both correct

Answer 15

\[3x+4\ge \:0\:\mathrm{for}\:x\ge \:-\frac{4}{3},\:\quad \mathrm{\therefore\:for}\:x\ge \:-\frac{4}{3}\quad \left|3x+4\right|=3x+4\]
\[3x+4<0\:\mathrm{for}\:x<-\frac{4}{3},\:\quad \mathrm{\therefore\:for}\:x<-\frac{4}{3}\quad \left|3x+4\right|=-\left(3x+4\right)\]
\[\mathrm{Evaluate\:the\:expression\:\in\:the\:following\:ranges:}\]
\[x<-\frac{4}{3},\:x\ge \:-\frac{4}{3}\]
\[-\left(-\left(3x+4\right)\right)=5x+4\quad :\quad x=0\]
\[-\left(3x+4\right)=5x+4\quad :\quad x=-1\]
combine the range
\[\left(x<-\frac{4}{3}\:\:\:\mathrm{and}\:\:\:\:x=0\right)\:\:\:\mathrm{or}\:\:\:\left(x\ge \:-\frac{4}{3}\:\:\:\mathrm{and}\:\:\:\:x=-1\right)\]
x=-1

Answer 16

well looking at that second equation I wrote:
-|3(0)+4|=5(0)+4
-|0+4|=0+4
-|4|=4
-4=4 <--this isn't a true equation so x=0 is definitely not a solution

Answer 17

are you understand @freckles

Answer 18

what does that means "are you understand @freckles "

Answer 19

nothing mean :)

Answer 20

well if you don't understand my explanation
here is another way to look at it @DecentNabeel
\[-|3x+4|=5x+4 \\ |3x+4|=-(5x+4) \\ \text{ we need } 5x+4 \le 0 \\ x \le \frac{-4}{5}\]
and x wasn't less than or equal to -4/5
but -1 is
so x=-1 is the only solution

Answer 21

well, this is getting interesting

Answer 22

oops 0 wasn't less than or equal to -4/5*

Answer 23

but I think what you meant to ask me earlier @DecentNabeel was "do you understand @freckles "

Answer 24

i have one question

|7x - 5|

are the two things 7x + 5 and -7x - 5 ???

Answer 25

|7x-5| can be 7x-5 or -7x+5
|7x-5| is 7x-5 only when 7x-5>=0
|7x-5| is -(7x-5) only when 7x-5<=0

Answer 26

ok thx

Answer 27

ima close it now

Answer 28

i said x=-1 is the solution..
but you said that are not correct..
then finally you are agree with me
:)

Answer 29

u guys have been awesome

Answer 30

I never disagreed with you @DecentNabeel

Answer 31

@DecentNabeel where above did I ever say x=-1 wasn't the solution

Answer 32

ok:)

Answer 33

@DecentNabeel I think you should reread the conversation above because you might have gotten lost somewhere along the way.

Answer 34

yes i cannot read the conversation above..
continue @freckles