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The number x satisfies 5x^2 + 4 = 3x + 9. Find the value of $(10x - 3)^2$.

 May 22, 2019
 #1
avatar+31 
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any 1 plz?

 May 23, 2019
 #2
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Use the Quadratic Formula to find the value of x in the first part. Then sub that value for x in the second part.

 May 23, 2019
 #3
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how do i know if i plug in  3+√109/10 or  3-√109/10  for 10x

 May 23, 2019
 #4
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+1

The number x satisfies 5x^2 + 4 = 3x + 9. Find the value of $(10x - 3)^2$.

 

Guest has given you a very good teaching answer.

And you have responded appropriately.

I am very pleased with both of you.

 

This is what i suggest.

Find the answer for x - yes I know there will be 2 answers but just leave them with the plus/minus answer. You will not need to seperate them.

You can work out both at onces.

 

You have x=   [3(+ or -)√109]/10       

now find 10x

then find 10x - 3

 

Now it is easy to square it.  Both answers will be the same.

.
 May 23, 2019
edited by Melody  May 23, 2019

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