SOLUTION: HI i need help with these questions.(Completing the square.) 1.)75x^2+35x-10=0 2.)4x^2-72x+324=0

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Question 711674: HI i need help with these questions.(Completing the square.)
1.)75x^2+35x-10=0
2.)4x^2-72x+324=0
Found 2 solutions by lynnlo, stanbon:
Answer by lynnlo(4176) (Show Source):
You can put this solution on YOUR website!
(1)x=1/5,-2/3
(2)x=9

Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
Completing the square.)
1.)75x^2+35x-10=0
25x^2 + 7x - 5 = 0
----
25x^2 + 7x = 5
25(x^2 + (7/25)x + ?) = 5 + 25*?
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Complete the square:
25(x^2 + 7/25 x + (7/50)^2) = 5 + 25(7/50)^2
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25(x+(7/50))^2 = 5 + 25(49/2500)
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25(x+(7/50))^2 = 5 + (49/100)
25(x+(7/50))^2 = (5*49/100)
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(x+(7/50))^2 = (49/500)
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x+(7/50) = 7/(10sqrt(5))
etc.
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2.)4x^2-72x+324=0
4x^2 -72x = -324
----
4(x^2-18x + ?) = -324 + 4*?
Complete the square:
4(x^2-18x+81) = -324 + 4*81
----
4(x-9)^2 = 0
------
x = 9 with multiplicity 2.
Cheers,
Stan H.
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