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Y^2-10+30 Prove that the value of the expression must be positive.

User Andres Abadia
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1 Answer

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18 votes

Answer:

Explanation:


y^2-10y+30=\\y^2-2(y)(5)+5^2-5^2+30=\\(y-5)^2-25+30=\\(y-5)^2+5


(y-5)^2\geq 0\\\Rightarrow\ (y-5)^2+5 > 0\\Thus,\ y^2-10y+30 > 0

User David Tang
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