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sqrt(3x^2-5x)=sqrt(x^2+2x+5) помогите

 Nov 20, 2016
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\(\sqrt{3x^2-5x}=\sqrt{x^2+2x+5}\) помогите

 

Firstly both expressions under the sqrts must be positive.  I'll think about that more later.

 

\(3x^2-5x=x^2+2x+5\\ 2x^2-7x-5=0\\ 2x^2-7x-5=0\\ \triangle=49+40=89\\ x=\frac{7\pm\sqrt{89}}{4}\)

 

(7+sqrt(89))/4 = 4.108495283014151

(7-sqrt(89))/4 = -0.608495283014151

 

 

x=\frac{7\pm\sqrt{89}}{4}

 

 3*(4.108495283014151)^2-5(4.108495283014151) = 30.096724056577831167 >0   The plus version is good

3*(-0.608495283014151)^2-5(-0.608495283014151) = 4.153275943422170167  >0   Good

By visual inspection I can see that the DH sides will be real.

 

 

So the answers are     \(x=\frac{7\pm\sqrt{89}}{4}\)

 

 

 

Here is the graph

https://www.desmos.com/calculator/vxqrjyw9xu​

 Nov 21, 2016

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