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|x2-1|=|x-1|

 

3|x-2|=2|x-3|

 

|4-x|=5

 

|2x-7|=|x-5|

 

|x2-x|=|x2-1|

 Jan 7, 2016

Best Answer 

 #7
avatar+26397 
+10

1. |x2-1|=|x-1|

|x21|=|x1|(x21)=(x1)(x+1)(|(x1)(x+1)|)2=(|x1|)2(square both sides)( (x1)(x+1) )2=(x1)2( (ab)2=a2b2 )(x1)2(x+1)2=(x1)2(x1)2(x+1)2(x1)2=0(x1)2[(x+1)21]=0(x1)2(x2+2x+11)=0(x1)2(x2+2x)=0(x1)2x(x+2)=0(x1)(x1)x(x+2)=01.x1=0x=12.x=03.x+2=0x=2

 

2. 3|x-2|=2|x-3|

3|x2|=2|x3|(3|x2|)2=(2|x3|)2(square both sides)32(x2)2=22(x3)2( (ab)2=a2b2 )9(x2)2=4(x3)29(x24x+4)=4(x26x+9)9x236x+36=4x224x+369x236x=4x224x5x212x=0x(5x12)=01.x=02.5x12=0x=125

 

3. |4-x|=5

 

|4x|=5(|4x|)2=(5)2(square both sides)(4x)2=25(±)4x=±5x=4±51.x=4+5x=92.x=45x=1

 

4. |2x-7|=|x-5|

|2x7|=|x5|(|2x7|)2=(|x5|)2(square both sides)(2x7)2=(x5)24x228x+49=x210x+253x218x+24=0:3x26x+8=0(x4)(x2)=01.x4=0x=42.x2=0x=2

 

5. |x2-x|=|x2-1|

|x2x|=|x21|x2x=x(x1)(x21)=(x1)(x+1)|x(x1)|=|(x1)(x+1)|( |x(x1)| )2=( |(x1)(x+1)| )2(square both sides)( x(x1) )2=( (x1)(x+1) )2( (ab)2=a2b2 )x2(x1)2=(x1)2(x+1)2x2(x1)2(x1)2(x+1)2=0(x1)2[x2(x+1)2]=0(x1)2(x2x22x1)=0(x1)2(2x1)=0(x1)(x1)(2x1)=01.x1=0x=12.2x1=0x=12

 

laugh

 Jan 8, 2016
edited by heureka  Jan 8, 2016
edited by heureka  Jan 8, 2016
 #1
avatar+8581 
0

are all the problems by itself? or am I suppose to combine them all??

 Jan 7, 2016
 #2
avatar+130477 
+5

These are always a little difficult to wrap one's head around.....!!!

 

They are all solved in pretty much the same manner  ....!!!

 

1.  abs (x^2 - 1) = abs (x - 1)

 

We have two  equations that result

 

x^2 - 1  =  x - 1                       and       x^2 -1  = -(x - 1)            working on both, we have

 

x^2  = x                                               x^2  - 1   = -x + 1

 

x^2 - x = 0                                          x^2 + x - 2  = 0

 

x(x-1)  = 0                                          (x +2) ( x-1)  = 0

 

So  x = 0 , 1                                      So  x = -2  and x = 1

 

The solutions are  x = -2, x = 0 and x = 1

 

Look at the graph of the solutions, here.........https://www.desmos.com/calculator/sanncuv3uw

 

 

cool cool cool

 Jan 7, 2016
 #3
avatar+130477 
+5

2.  3|x-2|=2|x-3|    divide both sides by 2

 

(3/2)|x-2|=lx-3|      as before, we have.....

 

(3/2)(x - 2)  = x -3                and          (3/2)(x - 2)  =  -(x - 3)

                       

                                                            (3/2)lx - 2 l  =  - x + 3

 

Multiply through by 2   in both equations.....

 

3(x -2) = 2x - 6                                     

 

3x - 6   = 4x - 6                                        3(x - 2)  = -2x + 6                               

 

The only solution to this is                     3x - 6    = -2x + 6

when x = 0  

                                                               5x  = 12

        

                                                                  x = 12/5  =  2 + 2/5  =  2.4

 

So the two solutions are  x = 0   and x  = 2.4

 

See the solution graphs, here.....   https://www.desmos.com/calculator/frf6guc36z

 

 

cool cool cool                              

 Jan 7, 2016
 #4
avatar+130477 
+5

3. |4-x|=5       this one is easy

 

Either

 

4 - x   = 5                          or                      4 - x  = -5

 

-x  = -1                                                         -x   = -9

 

x = 1                                                              x = 9

 

These solutions are easily verified in the original problem

 

 

cool cool cool         

 Jan 7, 2016
 #5
avatar+130477 
+5

4 .   |2x-7|=|x-5|

 

2x - 7    =    x  - 5                    or          2x - 7   = -(x - 5)

 

x  =  2                                                    2x - 7  = -x  + 5

 

                                                              3x  = 12

 

                                                                x = 4

 

Again......these are easily verified

 

 

cool cool cool

 Jan 7, 2016
 #6
avatar+130477 
+5

5.   |x^2-x|=|x^2-1|      similar to the first one, we have

 

x^2 - x   = x^2 - 1                  or             x^2 - x  =  - (x^2 - 1)

 

-x = -1                                                   x^2 - x  = -x^2 + 1

 

x = 1                                                   2x^2 - x - 1  = 0

 

                                                           (2x +1)  ( x - 1)  = 0

                     

                                                         Set each factor to  0

 

                                                            x = -1/2     [ x = 1    .....a repeated solution]

 

Here's the graph......https://www.desmos.com/calculator/kcbcpd3khj

 

 

 

cool cool cool

 Jan 7, 2016
 #7
avatar+26397 
+10
Best Answer

1. |x2-1|=|x-1|

|x21|=|x1|(x21)=(x1)(x+1)(|(x1)(x+1)|)2=(|x1|)2(square both sides)( (x1)(x+1) )2=(x1)2( (ab)2=a2b2 )(x1)2(x+1)2=(x1)2(x1)2(x+1)2(x1)2=0(x1)2[(x+1)21]=0(x1)2(x2+2x+11)=0(x1)2(x2+2x)=0(x1)2x(x+2)=0(x1)(x1)x(x+2)=01.x1=0x=12.x=03.x+2=0x=2

 

2. 3|x-2|=2|x-3|

3|x2|=2|x3|(3|x2|)2=(2|x3|)2(square both sides)32(x2)2=22(x3)2( (ab)2=a2b2 )9(x2)2=4(x3)29(x24x+4)=4(x26x+9)9x236x+36=4x224x+369x236x=4x224x5x212x=0x(5x12)=01.x=02.5x12=0x=125

 

3. |4-x|=5

 

|4x|=5(|4x|)2=(5)2(square both sides)(4x)2=25(±)4x=±5x=4±51.x=4+5x=92.x=45x=1

 

4. |2x-7|=|x-5|

|2x7|=|x5|(|2x7|)2=(|x5|)2(square both sides)(2x7)2=(x5)24x228x+49=x210x+253x218x+24=0:3x26x+8=0(x4)(x2)=01.x4=0x=42.x2=0x=2

 

5. |x2-x|=|x2-1|

|x2x|=|x21|x2x=x(x1)(x21)=(x1)(x+1)|x(x1)|=|(x1)(x+1)|( |x(x1)| )2=( |(x1)(x+1)| )2(square both sides)( x(x1) )2=( (x1)(x+1) )2( (ab)2=a2b2 )x2(x1)2=(x1)2(x+1)2x2(x1)2(x1)2(x+1)2=0(x1)2[x2(x+1)2]=0(x1)2(x2x22x1)=0(x1)2(2x1)=0(x1)(x1)(2x1)=01.x1=0x=12.2x1=0x=12

 

laugh

heureka Jan 8, 2016
edited by heureka  Jan 8, 2016
edited by heureka  Jan 8, 2016

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