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Solve the inequality 4x - 3x^2 < x^2 - 8x.

 May 26, 2020
 #1
avatar+912 
+1

If we add 8x to both sides we have

 

12x - 3x^2 < x^2

 

If we subtract x^2 from both sides we have

 

12x -2x^2 < 0

 

If we divide both sides by 2 we have

 

6x - x^2 < 0

 

If we divide both sides by x we have

 

6 - x < 0

 

Thus we have 6< x

 

Test.

 

Say x = 7.

 

28 - 3 * 49 < 49 - 56

 

-119 < -7 which is true.

 

If you don't understand naything feel free to ask.

 May 26, 2020
 #3
avatar+30322 
+1

Check your second inequality hugo - where you subtract x^2 from both sides.

Alan  May 26, 2020
 #2
avatar+30322 
+2

See if the graph helps:

 

 May 26, 2020

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