Question 160328: Hi, Can you please help me?
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Quadratic Equations ( You solve this problem same as quadratic equation)
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Solve 
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I replaced  with "u", and solved like a normal quadratic equation
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I found out that  and 
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since  , I found that 
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If we replace the "u" with "4" and (-1), it means  and  ,  and 
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I found the answers, but when I looked at the answers in the book, the book only had , why wouldn't , or did the book forget to mention
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Thanks ahead of time, Levi
Answer by checkley77(12844)   (Show Source):
You can put this solution on YOUR website! It's a very good idea to use proofs for ALL answers.
x - 3 (sqrt(x)) - 4 = 0
Let x=1:
Proof:
x-3sqrtx-4=0
1-3sqrt1-4=0
1-3*1-4=0
1-3-4=0
1-7=0
-6=0 not a valid proof.
Let x=-1
-1-3sqrt-1-4=0
1-3*i-4=0
-3-3i=0 not a valid proof.
Proof for x=16:
16-3sqrt16-4=0
16-3*4-4=0
16-12-4=0
16-16=0
0=0 a valid proof.
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