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What value should be added to the expression to create a perfect square? x^2 - 20x


Please show work, I don't just want handed the answer without explaination.


Thanks :)

Verified Answer :

wolf1728

To complete the square:
we take the coefficient ox "x" (which in this problem is -20)
we divide it by 2
square that number
then add it to both sides of the equation

-20 / 2 = -10
-10^2 = 100
then we add 100 to both sides of the equation:
x^2 -20x
x^2 -20x +100 = 100
*****************************************************
To get the roots of the equation, we take the square root of both sides:
(x -10) (x-10) = 10
(x-10) = square root (10)
x-10 =



3.1622776602




x1 =



13.1622776602


and don't forget that square root of 10 also equals  -3.1622776602



x2 = 10
-



3.1622776602
x2 = 



6.8377223398






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