Question 221482
y^2 -4y +4 = 9
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y^2 -4y -5 =0,,,,,,,,,,factor
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(y-5)(y+1) =0
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y= 5,,,-1
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check,,,,(5),,,5^2 -4*5 +4 = 9,,,,,25-20 +4 =9,,,,ok
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(-1),,,,(-1)^2 -4(-1) +4 = 1+4+4 =9,,,,,,ok
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If  we  use  thew  quadratic  formula
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a= 1,,,,b=-4,,,,c=-5
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x=[ -(-4) +/- sqrt{ (-4)^2 -4(1)(-5)}] / 2(1)
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x=[4 +/- sqrt{ 16+20}]/2
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x=[ 4+/- sqrt36] /2
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x= [4 +/- 6] /2
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x= 10/2=5,,,,,,-2/2=-1
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