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Find the smallest value of x such that x^2 + 10x + 25 = 18.

 Jun 28, 2021
 #1
avatar+121062 
+2

x^2   +  10x +  25  = 18

 

x^2  + 10x  + 7=   0

 

x =       [ -10  -  sqrt  ( 10^2  - 4 * 7 * )   ] / 2   =   

 

(-10  -  sqrt (72) )   /2    =

 

(-10 - 6sqrt 2)  / 2  =

 

-5    - 3sqrt (2)   ≈    .757

 

 

cool cool cool

 Jun 28, 2021
 #2
avatar+2244 
0

Nice solution, just one small correction. 

x^2 + 10x + 25 = 18

x^2 + 10x + 7 = 0

 

-10 +- sqrt(10^2 - 4*7*1)

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               2

 

-10 +- 2sqrt(18)

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               2

 

-5 - sqrt(18) = -9.242, not .757

I believe -.757 is the other solution. 

 

=^._.^=

catmg  Jun 29, 2021

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